Serotoninergic mechanisms in hypertension. Focus on the effects of ketanserin

Maternal serotonin: implications for the use of selective serotonin reuptake inhibitors during gestation†

Maternal use of antidepressants has increased throughout the last decades; selective serotonin reuptake inhibitors (SSRI) are the most prescribed antidepressants. Despite the widespread use of SSRI by women during reproductive age and pregnant women, an increasing amount of research warns of possible detrimental effects of maternal use of SSRI during pregnancy including low birthweight/small for gestational age and preterm birth. In this review, we revisited the impact of maternal use of SSRI during pregnancy, its impact on serotonin homeostasis in the maternal and fetal circulation and the placenta, and its impact on pregnancy outcomes-particularly intrauterine growth restriction and preterm birth. Maternal use of SSRI increases maternal and fetal serotonin. The increase in maternal circulating serotonin and serotonin signaling likely promotes vasoconstriction of the uterine and placental vascular beds decreasing blood perfusion to the uterus and consequently to the placenta and fetus with potential impact on placental function and fetal development. Several adverse pregnancy outcomes are similar between women, sheep, and rodents (decreased placental size, decreased birthweight, shorter gestation length/preterm birth, neonatal morbidity, and mortality) highlighting the importance of animal studies to assess the impacts of SSRI. Herein, we address the complex interactions between maternal SSRI use during gestation, circulating serotonin, and the regulation of blood perfusion to the uterus and fetoplacental unit, fetal growth, and pregnancy complications.

Synthesis of 3-(Pyridin-2-yl)quinazolin-2,4(1H,3H)-diones via Annulation of Anthranilic Esters with N-pyridyl Ureas

A new route for the synthesis of quinazolin-2,4(1H,3H)-diones and thieno [2,3-d]pyrimidine-2,4(1H,3H)-diones substituted by pyridyl/quinolinyl moiety in position 3 has been developed. The proposed method concluded in an annulation of substituted anthranilic esters or 2-aminothiophene-3-carboxylates with 1,1-dimethyl-3-(pyridin-2-yl) ureas. The process consists of the formation of N-aryl-N'-pyridyl ureas followed by their cyclocondensation into the corresponding fused heterocycles. The reaction does not require the use of metal catalysts and proceeds with moderate to good yields (up to 89%). The scope of the method is more than 30 examples, including compounds with both electron-withdrawing and electron-donating groups, as well as diverse functionalities. At the same time, strong electron-acceptor substituents in the pyridine ring of the starting ureas reduce the product yield or even prevent the cyclocondensation step. The reaction can be easily scaled to gram quantities.

Death-Associated Protein Kinase 3 Inhibitors Identified by Virtual Screening for Drug Discovery in Cancer and Hypertension

Death-associated protein kinase 3 (DAPK3) is a serine/threonine protein kinase that regulates apoptosis, autophagy, transcription, and actin cytoskeleton reorganization. DAPK3 induces morphological alterations in apoptosis when overexpressed, and it is considered a potential drug target in antihypertensive and anticancer drug development. In this article, we report new findings from a structure-guided virtual screening for discovery of phytochemicals that could modulate the elevated expression of DAPK3, and with an eye to anticancer drug discovery. We used the Indian Medicinal Plants, Phytochemistry and Therapeutics (IMPPAT), a curated database, as part of the methodology. The potential initial hits were identified based on their physicochemical properties and binding affinity toward DAPK3. Subsequently, various filters for drug likeness followed by interaction analysis and molecular dynamics (MD) simulations for 100 nsec were performed to explore the conformational sampling and stability of DAPK3 with the candidate molecules. Notably, the data from all-atom MD simulations and principal component analysis suggested that DAPK3 forms stable complexes with ketanserin and rotenone. In conclusion, this study supports the idea that ketanserin and rotenone bind to DAPK3, and show stability, which can be further explored as promising scaffolds in drug development and therapeutics innovation in clinical contexts such as hypertension and various types of cancer.

Dressings and topical agents for arterial leg ulcers

BACKGROUND

It is estimated that up to 1% of people in high-income countries suffer from a leg ulcer at some time in their life. The majority of leg ulcers are associated with circulation problems; poor blood return in the veins causes venous ulcers (around 70% of ulcers) and poor blood supply to the legs causes arterial ulcers (around 22% of ulcers). Treatment of arterial leg ulcers is directed towards correcting poor arterial blood supply, for example by correcting arterial blockages (either surgically or pharmaceutically). If the blood supply has been restored, these arterial ulcers can heal following principles of good wound-care. Dressings and topical agents make up a part of good wound-care for arterial ulcers, but there are many products available, and it is unclear what impact these have on ulcer healing. This is the third update of a review first published in 2003.

OBJECTIVES

To determine whether topical agents and wound dressings affect healing in arterial ulcers. To compare healing rates and patient-centred outcomes between wound dressings and topical agents.

SEARCH METHODS

The Cochrane Vascular Information Specialist searched the Cochrane Vascular Specialised Register, Cochrane Central Register of Controlled Trials, MEDLINE, Embase, Cumulative Index to Nursing and Allied Health Literature and Allied and Complementary Medicine databases, the World Health Organization International Clinical Trials Registry Platform and ClinicalTrials.gov trials register to 28 January 2019.

SELECTION CRITERIA

Randomised controlled trials (RCTs), or controlled clinical trials (CCTs) evaluating dressings and topical agents in the treatment of arterial leg ulcers were eligible for inclusion. We included participants with arterial leg ulcers irrespective of method of diagnosis. Trials that included participants with mixed arterio-venous disease and diabetes were eligible for inclusion if they presented results separately for the different groups. All wound dressings and topical agents were eligible for inclusion in this review. We excluded trials which did not report on at least one of the primary outcomes (time to healing, proportion completely healed, or change in ulcer area).

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted information on the participants' characteristics, the interventions, and outcomes using a standardised data extraction form. Review authors resolved any disagreements through discussion. We presented the data narratively due to differences in the included trials. We used GRADE to assess the certainty of the evidence.

MAIN RESULTS

Two trials met the inclusion criteria. One compared 2% ketanserin ointment in polyethylene glycol (PEG) with PEG alone, used twice a day by 40 participants with arterial leg ulcers, for eight weeks or until healing, whichever was sooner. One compared topical application of blood-derived concentrated growth factor (CGF) with standard dressing (polyurethane film or foam); both applied weekly for six weeks by 61 participants with non-healing ulcers (venous, diabetic arterial, neuropathic, traumatic, or vasculitic). Both trials were small, reported results inadequately, and were of low methodological quality. Short follow-up times (six and eight weeks) meant it would be difficult to capture sufficient healing events to allow us to make comparisons between treatments. One trial demonstrated accelerated wound healing in the ketanserin group compared with the control group. In the trial that compared CGF with standard dressings, the number of participants with diabetic arterial ulcers were only reported in the CGF group (9/31), and the number of participants with diabetic arterial ulcers and their data were not reported separately for the standard dressing group. In the CGF group, 66.6% (6/9) of diabetic arterial ulcers showed more than a 50% decrease in ulcer size compared to 6.7% (2/30) of non-healing ulcers treated with standard dressing. We assessed this as very-low certainty evidence due to the small number of studies and arterial ulcer participants, inadequate reporting of methodology and data, and short follow-up period. Only one trial reported side effects (complications), stating that no participant experienced these during follow-up (six weeks, low-certainty evidence). It should also be noted that ketanserin is not licensed in all countries for use in humans. Neither study reported time to ulcer healing, patient satisfaction or quality of life.

AUTHORS' CONCLUSIONS

There is insufficient evidence to determine whether the choice of topical agent or dressing affects the healing of arterial leg ulcers.

Is Mania the Hypertension of the Mood? Discussion of A Hypothesis

Beyond both being biphasic/bidirectional disorders (hypo)mania and essential hypertension share a surprising number of similarities and an overlap between their genetics, biological background, underlying personality and temperamental factors, precipitating factors, comorbidity and response to treatment, indicating a possibly partially shared biological background. Based on theoretical knowledge, similarities related to characteristics, manifestation and course, and the results of pharmacological studies related to the effects and side effects of pharmacotherapies used in the treatment of these two distinct disorders, the authors outline a hypothesis discussing the similar origins of these two phenomena and thus mania being the hypertension of mood in memory of Athanasios Koukopoulos, one of the greatest researchers and theoreticists of mania of all time.

Oh, the places you'll go! My many colored serotonin (apologies to Dr. Seuss)

Serotonin [5-hydroxytryptamine (5-HT)] has a truly fascinating history in the cardiovascular world. Discovered in the blood, 5-HT has long been appropriately regarded as a vasoconstrictor. A multitude of in vitro studies of isolated vessels support that addition of 5-HT causes vascular contraction. In only a few cases was 5-HT a vasodilator. Moreover, the potency and threshold of 5-HT causing contraction is increased in arteries from hypertensive vs. normotensive subjects, both animal and human. As such, we and others have hypothesized that 5-HT would contribute to hypertension by elevating arterial tone. In stark contrast to these decades of findings, we observed that a chronic infusion of 5-HT into conscious rats caused a reduction in blood pressure and nearly normalized blood pressure of experimentally hypertensive rats. Going back to the early work of Irvine Page, one of the scientists who discovered 5-HT, reveals an early recognized but never understood ability of 5-HT to reduce systemic blood pressure. Our laboratory, in collaboration with colleagues around the world, has dedicated itself to understanding the mechanisms of 5-HT-induced reduction in blood pressure. This manuscript takes you through a brief history of the discovery of 5-HT, in vitro serotonergic pharmacology of blood vessels, in vivo work with 5-HT and our studies that suggests the venous vasculature, potentially in combination with small arterioles, may be important to the actions of 5-HT in reducing blood pressure. 5-HT has certainly ended up in a place I never expected it to go.

Inflammation and Vascular Effects after Repeated Intratracheal Instillations of Carbon Black and Lipopolysaccharide

Inflammation and oxidative stress are considered the main drivers of vasomotor dysfunction and progression of atherosclerosis after inhalation of particulate matter. In addition, new studies have shown that particle exposure can induce the level of bioactive mediators in serum, driving vascular- and systemic toxicity. We aimed to investigate if pulmonary inflammation would accelerate nanoparticle-induced atherosclerotic plaque progression in Apolipoprotein E knockout (ApoE^-/-) mice. ApoE^-/- mice were exposed to vehicle, 8.53 or 25.6 μg nanosized carbon black (CB) alone or spiked with LPS (0.2 μg/mouse/exposure; once a week for 10 weeks). Inflammation was determined by counting cells in bronchoalveolar lavage fluid. Serum Amyloid A3 (Saa3) expression and glutathione status were determined in lung tissue. Plaque progression was assessed in the aorta and the brachiocephalic artery. The effect of vasoactive mediators in plasma of exposed ApoE^-/- mice was assessed in aorta rings isolated from naïve C57BL/6 mice. Pulmonary exposure to CB and/or LPS resulted in pulmonary inflammation with a robust influx of neutrophils. The CB exposure did not promote plaque progression in aorta or BCA. Incubation with 0.5% plasma extracted from CB-exposed ApoE^-/- mice caused vasoconstriction in aorta rings isolated from naïve mice; this effect was abolished by the treatment with the serotonin receptor antagonist Ketanserin. In conclusion, repeated pulmonary exposure to nanosized CB and LPS caused lung inflammation without progression of atherosclerosis in ApoE^-/- mice. Nevertheless, plasma extracted from mice exposed to nanosized CB induced vasoconstriction in aortas of naïve wild-type mice, an effect possibly related to increased plasma serotonin.

Dressings and topical agents for arterial leg ulcers

BACKGROUND

It is estimated that people in industrialised countries have a 1% chance of suffering from a leg ulcer at some time in their life. The majority of leg ulcers are associated with circulation problems; poor blood return in the veins causes venous ulcers (around 70% of ulcers) and poor blood supply to the legs causes arterial ulcers (around 22% of ulcers). Treatment of arterial leg ulcers is directed towards correcting the poor arterial blood supply, for example by correcting arterial blockages (either surgically or pharmaceutically). If the blood supply has been restored, these arterial ulcers can heal following principles of good wound care. Dressings and topical agents make up a part of good wound care for arterial ulcers but there are many products available and it is unclear what impact these have on ulcer healing. This is an update of a review first published in 2003.

OBJECTIVES

To determine whether topical agents and wound dressings affect healing in arterial ulcers. To compare healing rates, patient-centred outcomes and costs between wound dressings and topical agents.

SEARCH METHODS

For this update the Cochrane Peripheral Vascular Diseases Group Trials Search Co-ordinator searched the Specialised Register (last searched November 2014) and The Cochrane Central Register of Controlled Trials (CENTRAL) (the Cochrane Library) (2014, Issue 10).

SELECTION CRITERIA

Randomised controlled trials (RCTs), or controlled clinical trials (CCTs) evaluating dressings and topical agents in the treatment of arterial leg ulcers were eligible for inclusion. The participants had to have ulcers that were described as arterial, and the time to healing, proportion completely healed, or rate of reduction in ulcer area had to be reported. All wound dressings and topical agents were eligible for inclusion in this review.

DATA COLLECTION AND ANALYSIS

The two review authors independently extracted information on the participants' characteristics, the interventions, and outcomes using a standardised data extraction form. Disagreements between the review authors were resolved through discussion.

MAIN RESULTS

One trial met the inclusion criteria, which was a small trial that compared 2% ketanserin ointment in polyethylene glycol (PEG) with vehicle alone (PEG) control, changed twice a day in 40 participants with arterial leg ulcers. The overall quality of the evidence was low with a single small included study which showed inadequate reporting of the results and had too short a follow-up time (eight weeks) to be able to capture sufficient healing events to allow comparisons to be made. In addition, the study was of low methodological quality. The majority of the 'risk of bias' domains received an 'unclear' risk rating as very little information was provided in the text on the methods of the study. The trial demonstrated increased wound healing in the ketanserin group, compared with the control group, but the trial was too small and had too short a follow-up period (eight weeks) to be able to determine whether there was any difference in healing rates. It should also be noted that ketanserin is not licensed in all countries for use in humans.

AUTHORS' CONCLUSIONS

There is insufficient evidence to determine whether the choice of topical agent or dressing affects the healing of arterial leg ulcers.

One-month serotonin infusion results in a prolonged fall in blood pressure in the deoxycorticosterone acetate (DOCA) salt hypertensive rat

A 7-day infusion of serotonin (5-hydroxytryptamine, 5-HT) causes a sustained fall in elevated blood pressure in the male deoxycorticosterone acetate (DOCA)-salt rat. As hypertension is a long-term disease, we presently test the hypothesis that a longer (30 day) 5-HT infusion could cause a sustained fall in blood pressure in the established hypertensive DOCA-salt rat. This time period (∼4 weeks) was also sufficient to test whether 5-HT could attenuate the development of DOCA-salt hypertension. 5-HT (25 μg/kg/min; sc) or vehicle (Veh) was delivered via osmotic pump to (1) established DOCA-salt rats for one month, (2) Sprague-Dawley rats prior to DOCA-salt administration for one month, and blood pressure and heart rate measured telemetrically. On the final day of 5-HT infusion, free platelet poor plasma 5-HT concentrations were significantly higher in 5-HT versus Veh-infused rats, and mean arterial pressure was significantly lower in 5-HT-infused (135 ± 4 mmHg vs Veh-infused 151 ± 7 mmHg) established DOCA-salt rats. By contrast, 5-HT-infusion did not prevent the development of DOCA-salt hypertension (144 ± 7 mmHg vs Veh = 156 ± 6 mmHg). Isometric contraction of aortic strips was measured, and neither the potency nor maximum contraction to the alpha adrenergic receptor agonist phenylephrine (PE) or 5-HT were modified by infusion of 5-HT (established or preventative infusion), and maximum aortic relaxation to acetylcholine (ACh) was modestly but not significantly enhanced (∼15% improvement). This study demonstrates 5-HT is capable of lowering blood pressure in established DOCA-salt hypertensive rats over the course of one month in a mechanism that does not significantly modify or is dependent on modified vascular responsiveness. This finding opens the possibility that elevation of 5-HT levels could be useful in the treatment of hypertension.

Serotonin and blood pressure regulation

5-Hydroxytryptamine (5-HT; serotonin) was discovered more than 60 years ago as a substance isolated from blood. The neural effects of 5-HT have been well investigated and understood, thanks in part to the pharmacological tools available to dissect the serotonergic system and the development of the frequently prescribed selective serotonin-reuptake inhibitors. By contrast, our understanding of the role of 5-HT in the control and modification of blood pressure pales in comparison. Here we focus on the role of 5-HT in systemic blood pressure control. This review provides an in-depth study of the function and pharmacology of 5-HT in those tissues that can modify blood pressure (blood, vasculature, heart, adrenal gland, kidney, brain), with a focus on the autonomic nervous system that includes mechanisms of action and pharmacology of 5-HT within each system. We compare the change in blood pressure produced in different species by short- and long-term administration of 5-HT or selective serotonin receptor agonists. To further our understanding of the mechanisms through which 5-HT modifies blood pressure, we also describe the blood pressure effects of commonly used drugs that modify the actions of 5-HT. The pharmacology and physiological actions of 5-HT in modifying blood pressure are important, given its involvement in circulatory shock, orthostatic hypotension, serotonin syndrome and hypertension.

5-hydroxtryptamine receptors in systemic hypertension: an arterial focus

BACKGROUND

Serotonin (5-hydroxytryptamine [5-HT]) was named for its isolation from blood serum (sero-) and ability to contract smooth muscle (-tonin). Thus, its relationship with the cardiovascular system began with its discovery.

AIMS

This review will focus on the effects of 5-HT and its receptors in the vasculature, with a focus on their involvement in high blood pressure (hypertension). Two seemingly contradictory bodies of evidence exist that make it difficult to assign any one function to 5-HT in vascular control of blood pressure.

RESULTS

 In vitro, 5-HT is an established vasoconstrictor, the effects of which are amplified in hypertension. By contrast, 5-HT (or its precursor 5-hydroxytryptophan) lowers blood pressure when given chronically in vivo. We will discuss ideas that might help us understand these differences, discuss relatively new pharmacology parameters (e.g. biased, inverse agonism) as they pertain to 5-HT receptors, and pose questions that are vital to answer so as to understand the role played by 5-HT in control of blood pressure, especially as it pertains to vascular function.

CONCLUSIONS

Our goal is to understand if the actions of 5-HT in hypertension are physiologically and clinically relevant. The community understands 5-HT has complex cardiovascular effects, and clinical studies have proven equivocal in terms of the involvement of 5-HT. This article provides a balanced view of evidence/literature that illustrates involvement of 5-HT in hypertension as controversial. It contributes new pharmacological knowledge of 5-HT compounds, and poses timely questions as to how this field can move forward. The take home message is that the cardiovascular effects of 5-HT are markedly complex such that we have not yet answered the question of whether 5-HT is beneficial or detrimental to hypertension.

Increased sensitivity of serotonin on the voltage-dependent K+ channels in mesenteric arterial smooth muscle cells of OLETF rats

This study examined the mechanisms of hypertension in diabetes. We investigated the effects of serotonin (5-HT) on voltage-dependent K(+) (Kv) channel activity, vasoconstriction, 5-HT receptor expression levels, and the involvement of protein kinase C (PKC) in mesenteric arteries of Otsuka Long-Evans Tokushima fatty (OLETF) rats compared with Long-Evans Tokushima Otsuka (LETO) rats. Blood pressure, body weight, blood glucose level, and mesenteric arterial wall thickness were greater in OLETF rats. The 5-HT-induced vasoconstriction of mesenteric arteries was greater in OLETF rats than in LETO rats and inhibited by the 5-HT(2A) inhibitor inhibitor, ketanserin. The Kv currents in mesenteric arterial smooth muscle cells (MASMCs), determined using a perforated patch clamp technique, was inhibited by 1 mM 4-AP (42.5 +/- 4.1% vs. 63.5 +/- 2.3% in LETO vs. OLETF rats at +40 mV), but was insensitive to 1 mM TEA and 100 nM iberiotoxin. The inhibition of Kv current by 1 microM 5-HT in MASMCs was greater in OLETF rats than in LETO rats (17.1 +/- 2.2% vs. 33.2 +/- 2.7% in LETO vs. OLETF rats at +40 mV), and the inhibition was prevented by treatment with the PKCalpha- and beta- selective inhibitor, Gö6976. The expression level of 5-HT(2A), but not 5-HT(2B), receptor and the expression levels of total PKC, PKCbeta, and PKCepsilon, but not PKCalpha, were higher in the mesenteric arteries of OLETF rats compared with LETO rats. The enhanced expression of 5-HT(2A) receptor together with PKCbeta may promote mesenteric vasoconstriction and increase vascular resistance in OLETF rats.

The beginning of a fantastic, unanswered question: is 5-HT involved in systemic hypertension?

This essay examines the historical significance of an APS classic paper that is freely available online:

The love of a lifetime: 5-HT in the cardiovascular system

Serotonin [5-hydroxytryptamine (5-HT)] is an amine made from the essential amino acid tryptophan. 5-HT serves numerous functions in the body, including mood, satiety, and gastrointestinal function. Less understood is the role 5-HT plays in the cardiovascular system, although 5-HT receptors have been localized to every important cardiovascular organ and 5-HT-induced changes in physiological function attributed to activation of these receptors. This manuscript relates a few scientific stories that test the idea that 5-HT is important to the control of normal vascular tone, more so in the hypertensive condition. Currently, our laboratory is faced with two different lines of experimentation from which one could draw vastly different conclusions as to the ability of 5-HT to modify endogenous vascular tone and blood pressure. Studies point to 5-HT being important in maintaining high blood pressure, but other studies solidly support the ability of 5-HT to reduce elevated blood pressure. This work underscores that our knowledge of the functions of 5-HT in the cardiovascular system is significantly incomplete. As such, this field is an exciting one in which to be, because there are superb questions to be asked.

Different affinities of native alpha1B-adrenoceptors for ketanserin between intact tissue segments and membrane preparations

The pharmacological profiles of alpha1-adrenoceptors for ketanserin, prazosin, silodosin, and BMY 7378 (8-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-8-azaspiro[4,5]decane-7,9-dione dihydrochloride) were examined under different assay conditions. Among the tested antagonists and alpha1-adrenoceptors subtypes, ketanserin showed significantly lower affinity for the alpha1B-adrenoceptor subtype in intact tissue sampled from the rat tail artery, thoracic aorta, and cerebral cortex (functional pKB and binding pKi were approximately 6), than in cerebral cortex membrane preparations or whole cell and membrane preparations of alpha1B-adrenoceptor transfected human embryonic kidney 293T (HEK 293T) cells (pKi was approximately 8). In these tissues and cells, however, ketanserin showed a similar affinity (pKi = approximately 8) for alpha1A- and alpha1D-adrenoceptors even though the assays were conducted under different conditions. In contrast, the affinities of alpha1A-, alpha1B-, and alpha1D-adrenoceptors for prazosin, silodosin, and BMY 7378 did not significantly change under different assay conditions and in different tissues. The present study reveals that the pharmacological profiles of native alpha 1B-adrenoceptors for ketanserin is strongly influenced by the assay conditions and suggest that antagonist affinity is not necessarily constant.

Association of the 5-HT2A receptor gene polymorphism 102T/C with ischemic stroke

Serotonin (5-HT) has been implicated in a number of cardiovascular disorders due to its ability to induce vascular contraction and platelet aggregation through activation of the 5-HT2 receptor family. In this study, we investigated the association of stroke in a Scandinavian population with two common polymorphisms in the 5-HT2A receptor gene. The two polymorphisms under investigation, namely the 102T/C and the -1438A/G variations of the 5-HT2A receptor gene, were examined in a case control association study involving 99 stroke patients and a comparable number of controls. Among patients, the prevalence of the homozygous 102T/T genotype was significantly higher than in controls (28.3% vs 13.5%; p < 0.01). The allelic frequency of 102T carriers was also significantly higher in stroke patients than in controls (p = 0.002, OR = 1.88, 95% CI, 1.27-2.80). The association between the 102T allele and stroke was significant in both males and females. There was no association between stroke and the -1438A/G polymorphism. Taken together, this study indicates that the 102T/C polymorphism in the 5-HT2A receptor gene could be an independent risk factor for developing stroke.

Dressings and topical agents for arterial leg ulcers

BACKGROUND

It is estimated that people in industrialised countries have a 1% chance of suffering from a leg ulcer at some time in their life. The majority of leg ulcers are associated with circulation problems; poor blood return in the veins causes venous ulcers (around 70% of ulcers) and poor blood supply to the legs causes arterial ulcers (around 25% of ulcers). Treatment of arterial leg ulcers is directed towards correcting the poor arterial blood supply, for example, by surgically correcting arterial blockages, and by supporting ulcer healing using topical agents (medicines in cream/ointment) and wound dressings. There are a large number of topical agents and wound dressings available and it is unclear what impact these have on ulcer healing.

OBJECTIVES

To determine whether topical agents and wound dressings affect the rate of healing in arterial ulcers. To compare healing rates, costs and patient-centred outcomes between wound dressings and topical agents.

SEARCH STRATEGY

Potential trials were sought through the Specialised Trials Registers of the Cochrane Wounds Group (last searched April 2002), the Cochrane Peripheral Vascular Diseases Group (last searched November 2006) and the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library, Issue 4, 2006

SELECTION CRITERIA

Randomised controlled trials (RCTs), or controlled clinical trials (CCTs) of dressings and topical agents for arterial leg ulcers were eligible for inclusion. The participants had to have ulcers that were described as arterial, and the time to healing, proportion completely healed, or rate of reduction in ulcer area had to be reported. All wound dressings and topical agents were eligible for inclusion in this review.

DATA COLLECTION AND ANALYSIS

Information on the participants' characteristics, the interventions, and outcomes, as well as data on the trial methods, such as blinding of patients and clinicians, and allocation concealment were extracted using a standardised data extraction form.

MAIN RESULTS

One trial met the inclusion criteria. This small trial compared ketanserin ointment with vehicle alone, changed twice a day. The trial was too small and for too short a follow-up period to be able to determine whether there was any difference in healing rates.

AUTHORS' CONCLUSIONS

There is insufficient evidence to determine whether the choice of topical agent or dressing affects the healing of arterial leg ulcers. Inadequate description of the people in the one included trial means that the results cannot be easily applied to other clinical populations.

Evaluation of the serotonin receptor blocker methiothepin in broilers injected intravenously with lipopolysaccharide and microparticles

There has been considerable interest in the role of serotonin (5-hydroxytryptamine, 5-HT) in the pathogenesis of pulmonary hypertension due to episodes of primary pulmonary hypertension in humans linked to serotoninergic appetite-suppressant drugs. In this study, we investigated the effect of 5-HT on the development of pulmonary hypertension induced by injecting bacterial lipopolysaccharide (LPS; endotoxin) and cellulose microparticles intravenously, using the nonselective 5-HT(1/2)receptor, antagonist methiothepin. In Experiment 1, broilers selected for ascites susceptibility or resistance under conditions of hypobaric hypoxia were treated with methiothepin or saline, followed by injection of LPS, while recording pulmonary arterial pressure (PAP). In Experiment 2 ascites-susceptible broilers were treated with methiothepin or saline, followed by injection of cellulose microparticles, while recording PAP. In Experiment 3, an i.v. microparticle injection dose shown to cause 50% mortality was injected into ascites-susceptible and ascites-resistant broilers after methiothepin or saline treatment. Injecting methiothepin reduced PAP below baseline values in ascites-susceptible and ascites-resistant broilers, suggesting a role for 5-HT in maintaining the basal tone of the pulmonary vasculature in broilers. Injecting microparticles into the wing vein had no affect on the PAP in the broilers treated with methiothepin, suggesting that 5-HT is an important mediator in the pulmonary hypertensive response of broilers to microparticles. Furthermore, injecting an 50% lethal dose of microparticles into ascites-susceptible and ascites-resistant broilers pretreated with methiothepin resulted in reduced mortality. Serotonin appears to play a less prominent role in the pulmonary hypertensive response of broilers to intravenously injected LPS, indicating that other mediators within the innate response to inflammatory stimuli may also be involved. These results are consistent with our hypothesis that pulmonary hypertension syndrome ensues when vasoconstrictors, such as 5-HT, overwhelm the dilatory effects of vasodilators, such as NO, thereby effectively reducing the pulmonary vascular capacity of pulmonary hypertension syndrome-susceptible broilers.

5-Hydroxytryptamine receptors in the human cardiovascular system

The human cardiovascular system is exposed to plasma 5-hydroxytryptamine (5-HT, serotonin), usually released from platelets. 5-HT can produce harmful acute and chronic effects. The acute cardiac effects of 5-HT consist of tachycardia (preceded on occasion by a brief reflex bradycardia), increased atrial contractility and production of atrial arrhythmias. Acute inotropic, lusitropic and arrhythmic effects of 5-HT on human ventricle become conspicuous after inhibition of phosphodiesterase (PDE) activity. Human cardiostimulation is mediated through 5-HT4 receptors. Atrial and ventricular PDE3 activity exerts a protective role against potentially harmful cardiostimulation. Chronic exposure to high levels of 5-HT (from metastatic carcinoid tumours), the anorectic drug fenfluramine and its metabolites, as well as the ecstasy drug 3,4-methylenedioxymethamphetamine (MDMA) and its metabolite 3,4-methylenedioxyamphetamine (MDA) are associated with proliferative disease and thickening of cardiac valves, mediated through 5-HT2B receptors. 5-HT2B receptors have an obligatory physiological role in murine cardiac embryology but whether this happens in humans requires research. Congenital heart block (CHB) is, on occasion, associated with autoantibodies against 5-HT4 receptors. Acute vascular constriction by 5-HT is usually shared by 5-HT1B and 5-HT2A receptors, except in intracranial arteries which constrict only through 5-HT1B receptors. Both 5-HT1B and 5-HT2A receptors can mediate coronary artery spasm but only 5-HT1B receptors appear involved in coronary spasm of patients treated with triptans or with Prinzmetal angina. 5-HT2A receptors constrict the portal venous system including oesophageal collaterals in cirrhosis. Chronic exposure to 5-HT can contribute to pulmonary hypertension through activation of constrictor 5-HT1B receptors and proliferative 5-HT2B receptors, and possibly through direct intracellular effects.

5-HT in systemic hypertension: foe, friend or fantasy?

Since its discovery by Erspamer in the 1930s and identification by Page in the 1950s, 5-HT (5-hydroxytryptamine; serotonin) has been an elusive candidate as a substance that plays a role in the disease of high blood pressure, also known as hypertension. In both animal and human hypertension, arterial contraction to 5-HT is profoundly enhanced. Additionally, 5-HT is a vascular smooth muscle cell mitogen. Because both increased arterial contractility and smooth muscle growth contribute to the disease of hypertension, it is logical to believe that 5-HT is a potential cause of disease, and thus a foe. However, decades of research have produced conflicting results as to the potential role of 5-HT in hypertension. This review will discuss historical findings which both support and refute the involvement of 5-HT in hypertension, and pose some new questions that may reveal novel ways for 5-HT to modify vascular control of blood pressure.

Prenatal stress changes rat arterial adrenergic reactivity in a regionally selective manner

A suboptimal fetal environment has been linked to increased risk of cardiovascular disease in adulthood. We investigated whether intrauterine stress (IUS) alters the development of adrenergic reactivity in different types of rat arteries. Intrauterine stress was induced by ligation of the uterine arteries at day 13 of pregnancy in Wistar rats. First-order mesenteric, renal, femoral and saphenous arteries of the 21-day-old male offspring were studied in a myograph. IUS in the rat changes arterial adrenergic reactivity in a regionally selective manner. Adrenoceptor-mediated responses are altered in the renal artery. Maximal contractile responses to phenylephrine were increased, while sensitivity to the alpha(1)-adrenoceptor agonist was decreased. Intrauterine stress significantly reduced contractile responses to norepinephrine and enhanced relaxing responses to isoproterenol in the renal artery. Adrenergic responses were not modified in mesenteric, femoral and saphenous arteries. In the kidneys the densities of [(3)H]prazosin binding sites, periarterial adrenergic nerves and of the glomeruli were not altered after intrauterine stress at day 13 of gestation. The observed regionally selective alterations in arterial reactivity might link a suboptimal fetal environment to the development of cardiovascular disease in the adult.

Functions of 5-HT2A receptor and its antagonists in the cardiovascular system

The serotonin (5-hydroxytryptamine, 5-HT) receptors have conventionally been divided into seven subfamilies, most of which have several subtypes. Among them, 5-HT(2A) receptor is associated with the contraction of vascular smooth muscle, platelet aggregation and thrombus formation and coronary artery spasms. Accordingly, selective 5-HT(2A) antagonists may have potential in the treatment of cardiovascular diseases. Sarpogrelate, a selective 5-HT(2A) antagonist, has been introduced clinically as a therapeutic agent for the treatment of ischemic diseases associated with thrombosis. Molecular modeling studies also suggest that sarpogrelate is a 5-HT(2A) selective antagonist and is likely to have pharmacological effects beneficial in the treatment of cardiovascular diseases. This review describes the above findings as well as the signaling linkages of the 5-HT(2A) receptors and the mode of agonist binding to 5-HT(2A) receptor using data derived from molecular modeling and site-directed mutagenesis.

The serotonin transporter is present and functional in peripheral arterial smooth muscle

We tested the hypothesis that the 5-HT transporter (5-HTT) is present and functional in peripheral arterial smooth muscle. In aorta and mesenteric resistance arteries, real time RT-PCR and western analyses indicated the presence of 5-HTT mRNA and a 74 kDa 5-HTT protein. Immunohistochemistry localized the transporter to smooth muscle and endothelial cells. 5-HT and the metabolite 5-hydroxyindole acetic acid (5-HIAA) were detected in aorta, carotid, and superior mesenteric arteries using HPLC; the MAOA inhibitor pargyline significantly increased (over 400%) arterial 5-HT concentration. 5-HT was taken up by arteries in a time-dependent manner and uptake was independent of the endothelium, sympathetic nerves, and norepinephrine transporter. 5-HT-induced contraction of normal aorta was potentiated by the 5-HTT inhibitor fluvoxamine. A change in arterial 5-HTT function occurs in deoxycorticosterone (DOCA)-salt hypertension as the potency and threshold of 5-HT in contracting aorta from the DOCA-salt rat was increased by fluoxetine and fluvoxamine (1 micromol/L; DOCA fluvoxamine -log EC50 [mol/L] = 6.85 +/- 0.08, DOCA-control = 6.44 +/- 0.08); expression of transporter was significantly increased in aorta of DOCA salt rats (145% Sham). These studies show for the first time the presence of the 5-HTT in peripheral arterial smooth muscle and raise the question as to the function of the 5-HTT in regulating peripheral effects of 5-HT.

An open-label study of nefazodone treatment of major depression in patients with congestive heart failure

OBJECTIVES

To evaluate the feasibility of screening and recruiting patients with major depression and congestive heart failure (CHF) in a tertiary care cardiology hospital and to obtain preliminary efficacy, tolerability, and safety data for nefazodone treatment of a major depressive episode in CHF patients.

METHOD

We conducted a 12-week, open-label trial of nefazodone given in dosages up to 600 mg daily. We assessed patients at baseline, 1, 2, 4, 8, and 12 weeks. Measures used were the 17-item Hamilton Depression Rating Scale (HDRS), the Clinical Global Impression Scale, the Beck Depression Inventory, Spielberger's State-Trait Anxiety Inventory, and the Minnesota Living with Heart Failure Questionnaire. We also obtained pre- and poststudy ECGs, 24-hour Holter monitor recordings, and plasma levels of norepinephrine.

RESULTS

After screening 443 CHF patients, 28 patients with major depression met study eligibility criteria. The 23 patients who completed 4 or more weeks of medication showed significant improvement on all depression scales and in quality of life. Of 19 subjects who completed the full 12-week trial, 74% experienced a decline of 50% or more on HDRS scores. The completers also showed a significant reduction in heart rate, an increase in QT intervals (but not in the QTc), and a marginally significant decrease in plasma norepinephrine. There were no changes in heart rate variability.

CONCLUSIONS

It is feasible to screen and recruit CHF patients with major depression for an anti-depressant trial. Nefazodone seems sufficiently safe, tolerable, and efficacious to justify a larger, placebo-controlled trial.

Serotonin transporter gene functional polymorphism: a plausible candidate gene for increased vascular risk in depression

The evidence of increased vascular morbidity and mortality associated with depression has generated research interest in studying the mechanisms or causal pathways underlying this association. Recent advances in molecular genetics have demonstrated that serotonin transporter gene functional polymorphism may confer susceptibility for affective disorder as well as for some cardiovascular risk factors. Taking into account these genetic findings, this article proposes a hypothesis that serotonin transporter gene functional polymorphism may be a plausible candidate gene to study the genetic mechanisms of depression-related increased vascular morbidity and mortality. Future research projects to test this hypothesis is warranted.

Dressings and topical agents for arterial leg ulcers

BACKGROUND

It is estimated that people in industrialised countries have a 1% chance of suffering from a leg ulcer at some time in their life. The majority of leg ulcers are associated with circulation problems; poor blood return in the veins causes venous ulcers (around 70% of ulcers) and poor blood supply to the legs causes arterial ulcers (around 25% of ulcers). Treatment of arterial leg ulcers is directed towards correcting the poor arterial blood supply, for example, by surgically correcting arterial blockages, and by supporting ulcer healing using topical agents (medicines in cream/ointment) and wound dressings. There are a large number of topical agents and wound dressings available and it is unclear what impact these have on ulcer healing.

OBJECTIVES

To determine whether topical agents and wound dressings affect the rate of healing in arterial ulcers. To compare healing rates, costs and patient-centred outcomes between wound dressings and topical agents.

SEARCH STRATEGY

Publications describing (or potentially describing) randomised controlled trials (RCTs), or controlled clinical trials (CCTs) of dressings and topical agents for arterial leg ulcers were sought through the Specialised Trials Registers of the Cochrane Wounds Group (last searched January 2002) and the Cochrane Peripheral Vascular Diseases Group (last searched April 2002).

SELECTION CRITERIA

RCTs or CCTs (trials with non-randomised concurrent comparison groups) were eligible for inclusion. The participants had to have ulcers that were described as arterial, and the time to healing, proportion completely healed, or rate of reduction in ulcer area had to be reported. All wound dressings and topical agents were eligible for inclusion in this review.

DATA COLLECTION AND ANALYSIS

Information on the participants' characteristics, the interventions, and outcomes, as well as data on the trial methods, such as blinding of patients and clinicians, and allocation concealment were extracted using a standardised data extraction form.

MAIN RESULTS

One trial met the inclusion criteria. This small trial compared ketanserin ointment with vehicle alone, changed twice a day. The trial was too small and for too short a follow-up period to be able to determine whether there was any difference in healing rates.

REVIEWER'S CONCLUSIONS

There is insufficient evidence to determine whether the choice of topical agent or dressing affects the healing of arterial leg ulcers. Inadequate description of the people in the one included trial means that the results cannot be easily applied to other clinical populations.

Melatonin potentiates 5-HT(1A) receptor activation in rat hypothalamus and results in hypothermia

Effects of melatonin on both thermoregulatory responses and hypothalamic serotonin release were assessed in unanesthetized rats at three different ambient temperatures (Ta). Systemic administration of melatonin (30-120 mg/kg, i.p) caused a decrease in both colonic temperature and hypothalamic serotonin (5-HT) release in rats at both Ta 8 and 22 degrees C. The hypothermia was brought about by a decrease in metabolic rate at Ta 8 degrees C, whereas at Ta 22 degrees C the hypothermia was produced by both a decrease in metabolic rate and an increase in cutaneous temperature. However, in the heat (Ta 31 degrees C), neither thermoregulatory responses nor hypothalamic 5-HT release was affected by the same amount of administered melatonin. The melatonin-induced hypothermia and decreased 5-HT release in the hypothalamus were attenuated by selective depletion of brain 5-HT produced by intracerebroventricular injection of 5,7-dihydroxytryptamine. Furthermore, the melatonin-induced hypothermia was almost completely abolished by treatment with a 5-HT2A receptor agonist (DOI) or a 5-HT1A receptor antagonist [(-)-pindolol]. The data indicate that melatonin potentiates the 5-HT1A receptor activation in the hypothalamus and results in hypothermic effects which can be antagonized by the expected hyperthermic effect of DOI.

Serotonin-induced contraction in mesenteric resistance arteries: signaling and changes in deoxycorticosterone acetate-salt hypertension

Large arteries from hypertensive subjects are hyperresponsiveness to 5-hydroxytryptamine (5-HT). We tested the hypothesis that small arteries (225 micro ID) have a profile similar to conduit arteries, including signal transduction mechanisms and the 5-HT receptor subtype(s) mediating arterial contraction in normal and high blood pressure. Aorta and mesenteric arteries from Sprague-Dawley (232+/-6 micro ID), sham (229+/-7 micro ID; systolic blood pressure, 120+/-2 mm Hg), or deoxycorticosterone acetate (DOCA)-salt rats (255+/-11 micro ID, 192+/-8 mm Hg) were mounted in a wire-based myograph. In resistance arteries from Sprague-Dawley rats, the 5-HT2A receptor mediated contraction; agonists of the 5-HT1B, 5-HT1D, 5-HT1F, and 5-HT2B receptor were inactive. The tyrosine kinase inhibitor genistein (5 micromol/L, 4.8-fold rightward shift), PD 098,059 (10 micromol/L, 3.2-fold shift), phospholipase C inhibitor NCDC (100 micromol/L), and nifedipine (50 nmol/L) reduced maximum 5-HT-induced contraction in small arteries (4.5% and 53% control, respectively). As in aorta, 5-HT had a decrease in threshold (100-fold lower), increase in potency (11.6-fold leftward shift), and increase in efficacy (140% sham response) in small arteries from DOCA-salt rats compared with sham. Unlike in aorta, 5-HT-induced contraction in DOCA-salt small arteries was shifted competitively by the 5-HT2A receptor antagonist ketanserin (-log K(B) [mol/L] for both sham and DOCA-salt, 9.25+/-0.1), and contraction to the 5-HT2B agonist BW723C86 was not observed. Thus, the 5-HT2A receptor remains the contractile receptor in hypertension in small arteries. Although similarities were observed for large and small arteries, differences under the condition of DOCA-salt hypertension exist that may determine serotonergic compounds effective in lowering blood pressure.

The single dose pharmacokinetics and safety of deramciclane in healthy male volunteers

The pharmacokinetics and tolerability of a new putative non-benzodiazepine type anxiolytic compound deramciclane was studied in two consecutive studies. An open dose-escalation design was used to study doses from 0.2 to 50 mg in 18 healthy male volunteers. In the second study doses from 50 to 150 mg were investigated in 14 healthy males in a double-blind, placebo-controlled, dose escalation study. Deramciclane was rapidly absorbed from the GI-tract and T(max) was 2-4 h. The elimination half-life increased from about 20 h to about 32 h with the increasing dose. Nevertheless, the AUC(0-infinity) values increased linearly within the studies over the dose ranges of 3-50 and 50-150 mg. However, the increase was more than the ratio of the dose over the total dose range of 3-150 mg. Therefore, non-linear pharmacokinetics of deramciclane at high doses cannot be excluded. N-desmethyl deramciclane, which is the active metabolite of deramciclane, was determined in plasma. C(max) was reached at about 6 h. The AUC(0-48 h) for the N-desmethyl metabolite was about one third of the AUC(0-infinity) of the parent compound and the ratio remained constant at each dose level. Deramciclane was safe, and was well tolerated at each dose level.

Association of the serotonin transporter gene with serum cholesterol levels and heart disease

In a study of a group of elderly athletes we observed an unexpected association between serum cholesterol levels and the HTTLPR insertion/deletion polymorphism of the promoter region of the serotonin transporter gene (HTT, SLC6A4). As a follow-up we examined the potential association of this polymorphism with cholesterol and triglyceride levels, or heart disease, in two other groups of subjects. We examined the possible association between cholesterol levels and heart disease and genotypes of the HTTLPR insertion/deletion polymorphism of the promoter region of the HTT gene, in three independent study populations ranging from 42 to 90 years of age. For subjects 55 to 70 years of age in Group 1, cholesterol levels were significantly greater in the LS heterozygotes than either LL or SS homozygotes, indicating a heterosis effect (P </= 0.0001). This was replicated in Group 2 (P </= 0.015). Triglyceride levels were also significantly elevated in the LS subjects (P </= 0.001). In Groups 1 and 3 there was a significant association between LS heterozygosity and heart disease, angina, and heart attacks in subjects 70 years of age or less. All of these associations were absent in subjects >70 years of age. While these studies are preliminary and exploratory, they are consistent with a relationship of the HTT gene in cholesterol levels and a risk for heart disease. Replication of these findings in independent, epidemiologically based studies is required.

5-HT2B-receptor antagonist LY-272015 is antihypertensive in DOCA-salt-hypertensive rats

We previously demonstrated a change in the receptors mediating 5-hydroxytryptamine (5-HT)-induced contraction in arteries of deoxycorticosterone acetate (DOCA)-salt-hypertensive rats. Specifically, contraction to 5-HT is mediated primarily by 5-HT2A receptors in arteries from normotensive sham rats and by both 5-HT2A and 5-HT2B receptors in arteries from hypertensive rats. We hypothesized that the 5-HT2B receptor may play a role in maintaining the high blood pressure of DOCA-salt-hypertensive rats, and herein we provide data connecting in vitro and in vivo findings. The endothelium-denuded isolated superior mesenteric artery of DOCA-salt rats displayed a marked increase in maximum contraction to the newly available 5-HT2B-receptor agonist BW-723C86 compared with that of arteries from sham rats, confirming that the 5-HT2B receptor plays a greater role in 5-HT-induced contraction in arteries from DOCA-salt rats. In chronically instrumented rats, the 5-HT2B-receptor antagonist LY-272015 (0.3, 1.0, and 3.0 mg/kg iv at 30-min intervals) was given cumulatively 1 time/wk during 4 wk of continued DOCA-salt treatment. LY-272015 did not reduce blood pressure of the sham-treated rats at any time or dose. However, LY-272015 (1.0 and 3. 0 mg/kg) significantly reduced mean blood pressure in a subgroup of week 3 (-20 mmHg) and week 4 DOCA-salt (-40 mmHg) rats that had extremely high blood pressure (mean arterial blood pressure approximately 200 mmHg). Blockade of 5-HT2B receptors by in vivo administration of LY-272015 (3.0 mg/kg) was verified by observing reduced 5-HT-induced contraction in rat stomach fundus, the tissue from which the 5-HT2B receptor was originally cloned. These data support the novel hypothesis that 5-HT2B-receptor expression is induced during the development of DOCA-salt hypertension and contributes to the maintenance of severe blood pressure elevations.

The development of enhanced arterial serotonergic hyperresponsiveness in mineralocorticoid hypertension

OBJECTIVE

To demonstrate that the receptor in the rat mesenteric artery mediating contraction in response to 5-hydroxytryptamine switches from a 5-hydroxytryptamine-2A to a 5-hydroxytryptamine-2B receptor after 4 weeks of deoxycorticosterone and salt (1.0% NaCl plus 0.2% KCl) therapy, and, as an extension of these studies, to test the hypothesis that this switch occurs prior to the development of hypertension.

DESIGN

Rats were administered deoxycorticosterone-salt therapy or no therapy for 1, 3, 5, 7, or 28 days. Additionally, four groups of rats (sham-normal salt, sham-high salt, deoxycorticosterone-normal salt, and deoxycorticosterone-high salt) were administered therapy for 4 weeks (28 days) to distinguish between the roles of salt and blood pressure in serotonergic responsiveness.

METHODS

Superior mesenteric arteries were mounted in tissue baths for measurement of isometric contractile force; systolic blood pressure was measured by a tail-cuff method.

RESULTS

Systolic blood pressure was first elevated by deoxycorticosterone-salt therapy relative to that in sham controls on day 5. Contraction in response to phenylephrine was minimally altered after 7 days of deoxycorticosterone-salt therapy. By day 3, the tryptophan metabolite and putative 5-hydroxytryptamine-2B receptor agonist kynuramine contracted hypertensive arteries to a greater maximum (percentage of contraction induced by phenylephrine for rats administered deoxycorticosterone-salt therapy 48.5 +/- 16.0%) than that observed for arteries in sham-treated rats (9.7 +/- 6.2%); this was also observed for the ergot alkaloid ergonovine (deoxycorticosterone-salt 67.1 +/- 18.5% and sham treatment 14.5 +/- 9.1%); however, increase in reactivity to 5-hydroxytryptamine began on day 5. Ketanserin (a 5-hydroxytryptamine-2A antagonist with a low affinity for 5-hydroxytryptamine-2B receptor; 30 nmol/l) competitively inhibited contraction in response to 5-hydroxytryptamine of mesenteric arteries from sham-treated and deoxycorticosterone-salt-treated rats on days 1, 3, and 5 but had less effect on arteries in deoxycorticosterone-salt-treated rats by day 7, signifying that a change to a non-5-hydroxytryptamine-2A receptor had occurred. Sensitivities to 5-hydroxytryptamine and to ergonovine of deoxycorticosterone-treated rats fed a normal or high-salt diet for 28 days tended to increase, as did those of sham-treated rats fed a high-salt diet (with normal blood pressure). Contraction in response to phenylephrine was changed in arteries only from animals whose systolic blood pressure had been increased (deoxycorticosterone-normal salt and deoxycorticosterone-high salt groups).

CONCLUSIONS

These experiments support the hypothesis that the switch to ketanserin-insensitive 5-hydroxytryptamine-2 receptors likely occurs coincident with or just after the initial increase in blood pressure in the deoxycorticosterone-salt-treated rat.

The PACK trial: morbidity and mortality effects of ketanserin. Prevention of Atherosclerotic Complications

A total of 3899 patients over 40 years old who had documented intermittent claudication for at least 2 months and in whom the ratio of systolic blood pressure in the ankle to that in the arm was < 0.85 in both arteries of at least one foot were recruited in a double-blind, randomized, placebo-controlled trial after a single-blind run-in period of placebo treatment for 1 month. Trial drug was ketanserin 40 mg three times daily. The first primary event after randomization was the endpoint. Primary events were definite myocardial infarction, major stroke, amputation above the ankle, excision of ischaemic viscera, and death due to other vascular causes. There were 136 study endpoints in the 1930 patients treated with ketanserin, who were followed up for 2063 patient-years, and 132 study endpoints in the 1969 patients treated with placebo, who were followed up for 2129 patient-years. A harmful interaction of ketanserin and potassium-losing diuretics resulted in an increase in the number of deaths. After patients taking potassium-losing diuretics or antiarrhythmic agents were excluded, a secondary analysis showed that there were 65 endpoints in 1514 patients taking ketanserin and 87 in 1577 patients taking placebo, a reduction of 23% in the number of study endpoints in those taking ketanserin. The treadmill walking distance and ankle systolic pressure were measured in a predetermined subset of 594 patients. Complete datasets at the beginning and end of 1 year's treatment with ketanserin or placebo were available in 436 patients. There was no difference between the groups in the improvement in pain-free treadmill walking distance. The placebo effect on treadmill walking distance increased continuously for at least 1 year at the rate of about 15% every 6 months. There was no significant change in either group in the ankle systolic pressure at the end of the treatment period, but, in the group given ketanserin, brachial systolic pressure was decreased and the ankle/arm systolic pressure ratio therefore increased.

QT interval change with age in an overtly healthy older population

BACKGROUND

Prolonged QT interval on the surface electrocardiogram (ECG) is known to be associated with arrhythmias, coronary heart disease, and sudden cardiac death. Increased QT dispersion has also been related to arrhythymias which are more frequent in the elderly.

HYPOTHESIS

This study investigated the relationship between aging, QT interval, and QT dispersion.

METHODS

Normal resting ECGs were recorded from 96 healthy subjects (73 women, age range 40-102 years). No subject had symptoms or signs of heart disease and none was on medication affecting cardiac function. All had normal heart size on chest x-ray and normal electrolytes. Using a digitizing board, the RR and QT intervals were measured on each lead of each ECG, excluding only the leads in which the T wave was not visible. Mean RR, mean QT interval, and heart rate-adjusted QTc interval (standard Bazet's formula) were obtained from these measurements. Further, QT dispersion was calculated for each ECG as (1) the difference between the maximum and minimum QT interval, and (2) as the coefficient of variance of QT interval of all measurable leads.

RESULTS

A significant correlation between aging and prolonged QTc was noted in the total population (r = 0.43, p < 0.05), as well as in men (r = 0.4, p < 0.05) and women (r = 0.23, p < 0.05) separately. There was no association between QT dispersion and increasing age regardless of the method of calculation (r = -0.04, r = -0.08 respectively, both NS).

CONCLUSION

The rate-adjusted QT interval is prolonged with increasing age and may contribute to the increased risk of ventricular arrhythmias and cardiac mortality in elderly patients.

Hypotensive and reflex bradycardic effects of ketanserin, but not of prazosin, enhanced selectively in aging conscious rats

To determine whether cardiovascular effects of ketanserin are altered differently with aging as compared with those of prazosin, we recorded blood pressure (BP) and heart rate (HR) changes produced by treatment with either drug in three age groups of conscious Sprague-Dawley rats. BP was decreased more by ketanserin in 24-month than in 4- or 14-month-old rats, but was decreased equally by prazosin in all age groups. Pressor responses to phenylephrine (PE) were consistently abolished by both drugs, indicating that the greater hypotensive effects of ketanserin in 24-month-old rats were not due simply to alpha 1-adrenergic blockade. By contrast, baroreflex sensitivity, determined from reflex HR responses to infused angiotensin or sodium nitroprusside (SNP), was altered differently in old rats by ketanserin but not by prazosin. Whereas enhancement of reflex bradycardia by prazosin occurred at all ages, it was demonstrable only with ketanserin in older rats. Moreover, reflex tachycardia was unaffected by prazosin but was reversed to bradycardia by ketanserin in older rats. Because these differences persisted even after the data had been normalized to compensate for differences in baseline pressures, effects on HR reflexes were considered age dependent for ketanserin but not for prazosin. Although the underlying mechanisms are not clear, the selective enhancement of reflex bradycardia and reversal of reflex tachycardia in old rats by ketanserin, but not by prazosin, could explain why hypotensive responses to ketanserin increase with age whereas those to prazosin do not.

Pharmacological manipulation of cardiovascular responses to lower body negative pressure

To evaluate influences on blood volume distribution, atrial natriuretic peptide concentrations (ANP) and thoracic and leg electrical impedance at 2.5 (TI2.5 and LI2.5, respectively) and 100 kHz (TI100 and LI100, respectively) were monitored during administration of ketanserin, noradrenaline and trimetaphan combined with lower body negative pressure (LBNP) in 12 subjects. Administration of clinically relevant doses of ketanserin alone did not induce changes in mean arterial pressure (MAP) or in the central blood volume, as electrical impedance and ANP concentrations did not change. During continued infusion of ketanserin an increase in MAP from a mean of 90 (range 83-108) to 113 (range 98-138) mmHg was induced by noradrenaline, but TI2.5 [mean 45.6 (range 39.3-54.2)] and TI100 [mean 33.8 (range 27.5-38.5) omega] remainded stable until ganglionic blockade and LBNP were applied, when they increased by a mean of 3.1 (range 2.0-6.1) and 2.7 (range 1.1-4.2) omega, respectively (P < 0.05). Conversely, LI2.5 [mean 79.6 (range 74.1-89.4)] and LI100 [mean 56.7 (range 52.4-63.3) omega] decreased by a mean of 3.2 (range 1.2-8.0) and 2.3 (range 0.9-3.9) omega, ANP from a mean of 27.7 (range 10.2-62.7) to 12.7 (range 7.1-27.5) pmol.l-1 and MAP fell to a mean of 62 (range 42-70) mmHg (P < 0.05). The heart rate was a mean of 75 (range 69-77) beats.min-1 and did not change until LBNP, when it increased to a mean of 102 (range 78-104) beats.min-1, as presyncopal symptoms appeared. The data indicated that serotonergic blockade by ketanserin and alpha-sympathetic stimulation by noradrenaline did not affect blood volume distribution in normal humans, but that ganglionic blockade combined with LBNP reduced the central blood volume as leg volume increased; during central hypovolaemia tachycardia induced by ganglionic blockade did not prevent the fall in MAP, and thereby the appearance of presyncopal symptoms.

5-Hydroxytryptamine2B receptor mediates contraction in the mesenteric artery of mineralocorticoid hypertensive rats

Vascular responsiveness to 5-hydroxytryptamine (5-HT) is dramatically increased in hypertension. The hypothesis that augmented vasoconstriction to 5-HT in hypertension is due to a change in receptor subtype on vascular myocytes was tested. Mesenteric arteries from deoxycorticosterone acetate (DOCA)-salt hypertensive (systolic blood pressure > 180 mm Hg) and sham normotensive (systolic blood pressure < 130 mm Hg) rats were mounted in isolated tissue baths for measurement of isometric contractile force. The receptor mediating contraction in isolated mesenteric arteries from sham and DOCA-salt hypertensive rats is a member of the 5-HT2 family based on rank order of agonist potency (5-HT = alpha-methyl-5-HT [5-HT2 receptor agonist]>tryptamine>5-hydroxykynuramine). 5-HT was approximately 10-fold more potent in contracting mesenteric arteries from DOCA-salt hypertensive rats compared with arteries from sham normotensive rats. The tryptophan metabolite kynuramine, which possesses significant contractile activity at the 5-HT2B receptor, contracted hypertensive arteries significantly (50% of 5-HT maximum) but not sham arteries. Ketanserin (5-HT2A antagonist) competitively inhibited contraction to 5-HT in arteries from normotensive rats (-log dissociation constant [mol/L]; pKB = 8.54) but not from hypertensive rats (pKB > 6.5). Moreover, contraction to kynuramine was not blocked by ketanserin. Thus, under normal conditions, 5-HT2A receptors mediate contraction to 5-HT. However, in DOCA-salt hypertension, ketanserin-insensitive 5-HT2 receptors, possibly 5-HT2B receptors, mediate mesenteric arterial contraction to 5-HT.

Ketanserin inhibits depolarization-activated outward potassium current in rat ventricular myocytes

Ketanserin (KT), an antihypertensive agent, has been shown to prolong action potential duration (APD) and QT interval and to induce torsade de pointes in some patients. We previously suggested that the prolongation of APD could be due to KT inhibition of the fast component of the delayed rectifier current (IKr) in guinea-pig myocytes. However, in other tissue such as human atrium, Purkinje fibers, epicardial cells, and rat ventricular myocytes, the transient outward potassium current (Ito) is one of the major repolarizing currents. We investigated the possibility that KT could also increase APD by blocking Ito. Action potentials and membrane currents were recorded from rat ventricular myocytes known to have a large Ito by using whole-cell patch-clamp techniques. We found that KT (50 mumol/L) significantly prolonged APD at 50% repolarization by 218% (P < .05) and APD at 90% repolarization by 256% (P < .05) with no significant effect on other action potential parameters. Time-dependent Ito and sustained current (ISus) were measured in the presence of 400 nmol/L nisoldipine during depolarizing pulses to 40 mV from a holding potential of -100 mV every 10 seconds. KT resulted in a concentration- and time-dependent inhibition of charge area of Ito evaluated by integration with an EC50 of 8.3 mumol/L. The inhibitory effect of KT (10 mumol/L) was seen at voltages from 0 to 80 mV without any shift of the current-voltage relation of peak Ito. KT did not significantly change activation, inactivation, and reactivating curves of Ito. Kinetic analysis of Ito showed a biexponential fit of inactivation in 80.5% of total tracings studied at voltages between -30 and 80 mV (n = 149, R = .99 +/- .01). The inhibitory effect of KT was more prominent on charge areas of the slow component (Qs) than the fast component (Qf) of Ito (Qf = 33.2 +/- 6.2 s.pA and Qs = 235.5 +/- 7.4 s.pA for the control condition; 12.4 +/- 4.3 and 59.6 +/- 17 s.pA for KT at 40 mV; n = 4). The binding association (k) and dissociation (l) constants at 40 mV were 9.0 +/- 0.9x10(6) M-1.s-1 and 86.6 +/- 0.3 s-1, respectively. KT also blocked ISus in a dose-dependent manner with an EC50 of 11.2 mumol/L and had no significant effect on both the inward rectifier potassium current and the L-type calcium current.(ABSTRACT TRUNCATED AT 400 WORDS)

Interactions between serotonin and endogenous and exogenous noradrenaline in the human forearm

We investigated the interactions between serotonin (5-hydroxytryptamine, 5-HT) and exogenous or endogenous noradrenaline (NA) in the forearm of normotensive volunteers (n = 24), using venous occlusion plethysmography. Endogenous release of NA was stimulated by lower body negative pressure (LBNP; -10, -20 and -40 mmHg) and by intra-arterial (i.a.) infusions of tyramine (0.1 to 1 microgram/kg/min). Exogenous NA was infused in cumulative doses (0.3 to 10 ng/kg/min). All experiments were performed in the presence of either vehicle (0.4 mL/min), sodium nitroprusside (SNP; 3 or 5 ng/kg/min), or 5-HT (0.1 or 1 ng/kg/min). NA or 5-HT (1 ng/kg/min) were also infused with the selective 5-HT2 receptor antagonist ritanserin (500 ng/kg/min). Angiotensin II (Ang II; 0.03 to 0.3 ng/kg/min) was given as a vasoconstrictor control (n = 6). Vasoconstriction to exogenous NA was significantly enhanced by 5-HT (1 ng/kg/min; p < 0.05) in one group of subjects, but this could not be reproduced in a second group. In contrast, the vasoconstrictor responses to endogenous NA remained unaffected by 5-HT. SNP caused the same degree of vasodilation as 5-HT, and was followed by a similar response to NA. Ritanserin did not alter the vasoconstriction to infused NA, nor vasoconstriction to infused NA when combined with 5-HT. The vasoconstrictor response to Ang II was not influenced by 5-HT (0.1 ng/kg/min). Apparently, a synergistic effect between 5-HT and NA in the periphery involves a nonspecific mechanism. The latter seems to be confined to infused NA. The precise role of the 5-HT2 receptor in this interaction could not be elucidated.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of sarpogrelate on serotonin-induced increases in cytosolic Ca2+ in cultured rat mesangial cells

The effects of the new 5-HT2A receptor antagonist sarpogrelate on the cellular action of serotonin were examined in cultured rat mesangial cells by measuring cytosolic free calcium concentration ([Ca2+]i). Sarpogrelate inhibited serotonin-induced increases in [Ca2+]i in a concentration-dependent manner. M1, a major metabolite of sarpogrelate, also exhibited an inhibitory effect exceeding that of sarpogrelate. The inhibitory effects of sarpogrelate and M1 were abolished by washing out these compounds. In contrast, the increase in [Ca2+]i induced by angiotensin II or arginine vasopressin was not affected by pretreatment of the cells with sarpogrelate or M1. These results suggest that sarpogrelate and its major metabolite (M1) act as reversible and specific 5-HT2A receptor antagonists against the contractile action of platelet-derived serotonin in mesangial cells.

Pineal stimulation produces both hypertension and tachycardia in rats

In anesthetized rats, electrical stimulation of pineal gland elicited proportional hypertension and tachycardia, which could be mimicked by microinjection of an excitatory amino acid, kainic acid (0.3 micrograms), into the pineal gland. The hypertension induced by pineal stimulation was antagonized by either spinal transection or postsynaptic blockade of serotonin receptors, while the tachycardia induced by pineal stimulation was antagonized by either serotonin receptor antagonism, bilateral vagotomy or spinal transection. In addition, postsynaptic blockade of serotonin receptors with cyproheptadine (2-5 mg/Kg, IV) produced both hypotension and bradycardia, while stimulation of 5-HT receptors with DOI (10-250 micrograms/Kg, IV) produced both hypertension and tachycardia in rats. The results indicate that pineal stimulation activates brain 5-HT receptors and results in sympathetic stimulation or parasympathetic inhibition which leads to hypertension and tachycardia in rats.

Serotonergic mechanisms in hypertension

Serotonin and abnormal serotonergic activity (both central and peripheral) may play a role in pathogenesis of essential hypertension. Serotonin acts chiefly via three types of receptors namely S1, S2 and S3 serotonergic receptors. Besides being vasoactive, it has some inotropic and chronotropic properties and also affects blood rheology. It has stimulating effect on renin and aldosterone secretion. The action of other vasoactive substances like norepinephrine and angiotensin II are amplified. All these physiological effects of serotonin strongly support the hypothesis that it may be involved in hypertension. The advent of serotonin antagonists in lowering blood pressure has further substantiated this hypothesis.

Long-term hemodynamic effects at rest and during exercise of newer antihypertensive agents and salt restriction in essential hypertension: review of epanolol, doxazosin, amlodipine, felodipine, diltiazem, lisinopril, dilevalol, carvedilol, and ketanserin

Hypertension is due to disturbance of the complex interplay between numerous known and unknown mechanisms that normally control blood pressure. Antihypertensive agents may, therefore, reduce blood pressure through widely different actions and, at the same time, elicit counterregulatory responses. This is a review of the long-term hemodynamic effects at rest as well as during exercise of nine relatively new antihypertensive compounds: a beta-blocker (epanolol), an alpha-receptor blocker (doxazosin), two double-acting compounds (dilevalol and carvedilol), three calcium antagonists (amlodipine, felodipine, and diltiazem), an angiotensin-converting enzyme inhibitor (lisinopril), a serotonin antagonist (ketanserin), and low-salt diet as a nonpharmacological treatment in 171 patients with mild to moderate essential hypertension. The results in the treatment groups are compared to the hemodynamic changes seen in 28 hypertensive patients left untreated for 10 years. The patient populations of the different groups were comparable. The invasive hemodynamic technique, including intraarterial blood pressure recording and measurements of cardiac output by Cardigreen, was the same in all studies. While blood pressure remained nearly unchanged in the untreated group, all antihypertensive compounds induced significant and sustained blood pressure reduction both at rest and during exercise. The modest reduction (3-5%) in blood pressure during a low-salt diet was also statistically significant. This review shows the multiplicity of the long-term hemodynamic changes, ranging from a reduction in cardiac output to peripheral vasodilatation, during chronic antihypertensive therapy. In untreated hypertensives, the cardiac output is reduced by 1-2% per year and total peripheral resistance is increased by 2-3% per year. The review also focuses on counterregulatory responses and modify the initial reduction in blood pressure after drug treatment for hypertension. It is concluded that proper understanding of the hemodynamic effects of antihypertensive agents is useful in the selection of the right treatment for specific groups of hypertensive patients.

Serotonin-induced platelet aggregation predicts the antihypertensive response to serotonin receptor antagonists

The 5-HT2-receptor antagonist ketanserin (20-40 mg b.i.d.) was administered to 62 patients of both sexes with uncomplicated primary hypertension. After 4 weeks of treatment about 50% of the patients had reached the target diastolic blood pressure of 90 mm Hg or below. Interindividual variability was large. In a retrospective analysis the variability could not be explained by sex or the dose of ketanserin. There was a weak association between age and systolic blood pressure response (r = 0.24; P = 0.06), which could be entirely accounted for by the higher base line blood pressure in the elderly patients. In one group of patients (n = 12), the ex vivo aggregation to serotonin (10(-6) M) was studied during treatment with placebo and ketanserin. Ketanserin completely inhibited 5-HT-induced aggregation in all patients. There was a close correlation between the area under the 5-HT-induced platelet aggregation curve during placebo and the subsequent reduction in diastolic blood pressure after 4 weeks of treatment with ketanserin. The present data suggest that the blood pressure response to ketanserin can be predicted from the ex vivo sensitivity of platelets to serotonin. By implication, they also support a role for serotonergic mechanisms in hypertension.

Increased activity of the GABAergic system in selected brain areas after chronic propranolol treatment in spontaneously hypertensive rats

The influence of chronically administered propranolol on the functional state of the gamma-aminobutyric acid-ergic (GABAergic) system in spontaneously hypertensive rats was studied and compared with the effect of dihydralazine. GABA content, synthesis and turnover rate in selected brain areas were assessed. Hypotensive activity of propranolol and dihydralazine after injection of GABA antagonist pictrotoxin was examined in acute experiment. Prolonged administration of propranolol increased GABA content, synthesis and turnover rate in the hypothalamus and the pons-medulla. After chronic injections of dihydralazine there was no change in GABA indices. Antihypertensive activity of dihydralazine in picrotoxin-treated animals remained unchanged. On the contrary, picrotoxin suppressed the propranolol-induced decrease in blood pressure. Our results indicate that propranolol increases GABAergic system activity. Therefore, we conclude that down-regulation of the GABAergic system in hypertension may be compensated by the regulatory action of propranolol.

Effect of chronic administration of dexfenfluramine on blood pressure in salt-sensitive rats

Chronic administration of dexfenfluramine, at a relatively low daily dose, slowed the development of salt-induced elevation of blood pressure in salt-sensitive (Dahl DS and Rapp SS) rats. This effect could not be accounted for by drug-related anorexia alone. Elevated serotonin activity, possibly in the brain, may underlie this antihypertensive action of dexfenfluramine.

Ocular hypotensive actions of serotonin antagonist-ketanserin analogs

A series of ketanserin analogs were studied for their effects on intraocular pressure (IOP) recovery curve of rabbits infused with hypertonic saline. Eight out of 31 compounds tested showed a marked delay in IOP recovery indicating that they are potential antiglaucoma agents. Five out of eight compounds showed equal suppression of the IOP recovery curves of treated and contralateral eyes indicating that these compounds could be absorbed systemically to affect the IOP of the contralateral eye. There were three compounds (GC 679, GC 646, and GC 526) which showed more suppression of the IOP recovery curve of the treated eye than that of the contralateral eye, indicating that these drugs might act primarily at the local site to lower the IOP. Therefore, these three compounds could produce antiglaucoma actions with little systemic side effects, if any.

Antihypertensive effects of chronic 5-hydroxytryptamine (5-HT2) receptor blockade with irindalone in the spontaneously hypertensive rat

The present study was conducted to evaluate the antihypertensive effects of irindalone, a potent 5-HT2-receptor blocking agent with weak alpha 1-adrenoceptorblocking properties. Young spontaneously hypertensive rats (SHR) received irindalone in the food (daily intake estimated to 10 mg/kg) for 10 weeks and older SHR received irindalone subcutaneously for 2 weeks (3 mg/kg/day by osmotic pump). The indirect systolic blood pressure was measured each week (tail plethysmography) and at the end of the intervention periods the direct intraarterial blood pressure was measured in conscious rats. Subsequently a dose-response curve of pressor responses to phenylephrine was constructed in pithed rats. Chronic oral treatment with irindalone reduced the development of hypertension but influenced neither body weight nor heart weight. The subcutaneous treatment with irindalone reduced the blood pressure in relatively older SHR compared with controls. Pressor responses to phenylephrine were antagonized in rats receiving oral treatment. However, during subcutaneous treatment with irindalone the dose-response curve to phenylephrine was not influenced, suggesting that the blood pressure reduction was not directly related to a concomitant alpha 1-adrenoceptor blockade. These results demonstrate that irindalone effectively reduces the blood pressure in SHR and that no tolerance develops to its antihypertensive effects. Since the blood pressure reduction, at least following subcutaneous treatment, was not directly related to a concomitant alpha 1-blockade, it is suggested that the 5-HT2-receptor blockade may be of relevance for the antihypertensive effect.

Effect of ketanserin on cerebral blood flow autoregulation in healthy volunteers

The effect of a clinically relevant dose of ketanserin (10 mg as a bolus followed by an infusion of 6 mg/h) on cerebral blood flow (CBF) and CBF autoregulation was examined in 12 healthy volunteers. Changes in CBF were estimated by the cerebral arteriovenous-oxygen saturation difference method, while mean arterial blood pressure (MABP) was increased by norepinephrine and decreased by ganglionic blockade (trimethaphan camphosulphonate) combined with lower body negative pressure one hour after the infusion of ketanserin. During ketanserin infusion, MABP fell insignificantly by 2.5 mmHg (6 to -2), while CBF rose insignificantly by 5 ml/100 g/min. Autoregulation was preserved in all volunteers. CO2-correction factors from 0 to 4.6% CBF/0.1 kPa were used. The lower limit of CBF autoregulation was 82 mmHg (80-86) with an SE of 3 mmHg (1-5) similar to a previous control group of healthy volunteers. Aside from a major decrease in MABP in one subject, no adverse side effects were observed. The present study shows that CBF autoregulation is maintained during ketanserin infusion.