Chronic fetal exposure to caffeine altered resistance vessel functions via RyRs-BKCa down-regulation in rat offspring

Chronotropic and vasoactive properties of the gut bacterial short-chain fatty acids in larval zebrafish

Short-chain fatty acids (SCFAs) produced by the gut bacteria have been associated with cardiovascular dysfunction in humans and rodents. However, studies exploring effects of SCFAs on cardiovascular parameters in the zebrafish, an increasingly popular model in cardiovascular research, remain limited. Here, we performed fecal bacterial 16S sequencing and gas chromatography/mass spectrometry (GC-MS) to determine the composition and abundance of gut microbiota and SCFAs in adult zebrafish. Following this, the acute effects of major SCFAs on heart rate and vascular tone were measured in anesthetized zebrafish larvae using fecal concentrations of butyrate, acetate, and propionate. Finally, we investigated if coincubation with butyrate may lessen the effects of angiotensin II (ANG II) and phenylephrine (PE) on vascular tone in anesthetized zebrafish larvae. We found that the abundance in Proteobacteria, Firmicutes, and Fusobacteria phyla in the adult zebrafish resembled those reported in rodents and humans. SCFA levels with highest concentration of acetate (27.43 µM), followed by butyrate (2.19 µM) and propionate (1.65 µM) were observed in the fecal samples of adult zebrafish. Immersion in butyrate and acetate produced a ∼20% decrease in heart rate (HR), respectively, with no observed effects of propionate. Butyrate alone also produced an ∼25% decrease in the cross-sectional width of the dorsal aorta (DA) at 60 min (*P < 0.05), suggesting compensatory vasoconstriction, with no effects of either acetate or propionate. In addition, butyrate significantly alleviated the decrease in DA cross-sectional width produced by both ANG II and PE. We demonstrate the potential for zebrafish in investigation of host-microbiota interactions in cardiovascular health.NEW & NOTEWORTHY We highlight the presence of a core gut microbiota and demonstrate in vivo short-chain fatty acid production in adult zebrafish. In addition, we show cardio-beneficial vasoactive and chronotropic properties of butyrate, and chronotropic properties of acetate in anesthetized zebrafish larvae.

The causal relationship between blood metabolites and rosacea: A Mendelian randomization

BACKGROUND

An increasing amount of research demonstrates that metabolic disorders are related to rosacea. However, the correlations and causal relationships among them remain unknown.

METHODS

We conducted not only forward 2-sample MR (Mendelian randomization) analyses but also reverse MR analyses which showed positive results in the forward MR analysis. In the forward MR analyses, inverse-variance weighted (IVW) and MR-Egger were performed as MR analyses. Cochran's Q test and the MR-Egger Intercept were used for sensitivity analyses. Concerning reverse MR analyses, IVW, MR-Egger, weighted median, simple mode, and weighted mode were applied. Cochran's Q test, MR-Egger Intercept, and MR pleiotropy residual sum and outlier (MR-PRESSO) outlier test were applied as sensitivity analyses.

RESULTS

A total of 24 metabolites and 1 metabolite ratio were shown to have a causal effect on rosacea. N-lactoyl phenylalanine (N-Lac-Phe) was estimated as statistically significant by Bonferroni correction. Interestingly, we found three metabolites that were negatively associated with rosacea, especially caffeine, which are in line with the results of a large cohort study of females. For reverse MR analysis, we revealed that rosacea could potentially decrease the generation of two metabolites: octadecenedioate (C18:1-DC) and methyl vanillate sulfate.

CONCLUSION

This study identified blood metabolites that may be associated with the development of rosacea. However, the exact mechanism by which these positive metabolites influence rosacea remains uncertain due to the paucity of experimental investigations. The combination of genetics and metabolomics offers novel viewpoints on the research of underlying mechanisms of rosacea and has significant value in screening and prevention of rosacea.

Genotoxic effects of caffeine in female mice exposed during pregnancy and lactation period and their offspring

Caffeine is a widely consumed substance, and there is a discussion about its effects when ingested by women during pregnancy and lactation. We aimed to identify the genotoxic effects of caffeine in female mice that consumed it during pregnancy and lactation periods and its consequences in their offspring. Thirty-six couples of Swiss mice received water or caffeine (0.3 and 1.0 mg/mL) treatment during pregnancy and lactation. The male and female offspring were divided into 12 groups according to the treatment administered to the female mice. Genotoxicity was assessed using the comet assay and the micronucleus test. Both doses of caffeine showed genotoxic effects in pregnant and lactating mice groups compared to groups not administered caffeine. In relation to offspring, it can be observed that females and males of the offspring had low weight in early life. In both female and male offspring, genotoxicity was detected in the blood, liver, and kidney tissues. Thus, from the present study, we can suggest that the caffeine consumed by female mice during the periods of pregnancy and lactation led to genotoxic effects in their offspring.

Aging-induced down-regulation of Pka/Bkca pathway in rat cerebral arteries

The incidence of cerebrovascular diseases increases significantly with aging. This study aimed to test the hypothesis that aging may influence the protein kinase A (PKA)-dependent vasodilation via RyR/BKCa pathway in the middle cerebral arteries (MCA). Male Sprague-Dawley rats were randomly divided into control (4-6 month-old) and aged (24-month-old) groups. The functions of MCA and ion channel activities in smooth muscle cells were examined using myograph system and patch-clamp. Aging decreased the isoproterenol/forskolin-induced relaxation in the MCA. Large-conductance Ca2+-activated-K+ (BKCa) channel inhibitor, iberiotoxin, significantly attenuated the forskolin-induced vasodilatation and hyperpolarization in the young group, but not in the aged group. The amplitude and frequency of spontaneous transient outward currents (STOCs) were significantly decreased in the aged group. Single channel recording revealed that the mean open time of BKCa channels were decreased, while an increased mean closed time of BKCa channels were found in the aged group. The Ca2+/voltage sensitivity of the channels was decreased accompanied by reduced BKCa α and β1-subunit, the expression of RyR2, PKA-Cα and PKA-Cβ subunits were also declined in the aged group. Aging induced down-regulation of PKA/BKCa pathway in cerebral artery in rats. The results provides new information on further understanding in cerebrovascular diseases resulted from age-related cerebral vascular dysfunction.

Aging-Induced Down-Regulation of PKA/BKCa Pathway in Rat Cerebral Arteries

The incidence of cerebrovascular diseases increases significantly with aging. This study aimed to test the hypothesis that aging may influence the protein kinase A (PKA)-dependent vasodilation via RyR/BKCa pathway in the middle cerebral arteries (MCA). Male Sprague-Dawley rats were randomly divided into control (4-6 month-old) and aged (24-month-old) groups. The functions of MCA and ion channel activities in smooth muscle cells were examined using myograph system and patch-clamp. Aging decreased the isoproterenol/forskolin-induced relaxation in the MCA. Large-conductance Ca(2+)-activated-K(+) (BKCa) channel inhibitor, iberiotoxin, significantly attenuated the forskolin-induced vasodilatation and hyperpolarization in the young group, but not in the aged group. The amplitude and frequency of spontaneous transient outward currents (STOCs) were significantly decreased in the aged group. Single channel recording revealed that the mean open time of BKCa channels were decreased, while an increased mean closed time of BKCa channels were found in the aged group. The Ca(2+)/voltage sensitivity of the channels was decreased accompanied by reduced BKCa alpha and beta1-subunit, the expression of RyR2, PKA-Calpha and PKA-Cbeta subunits were also declined in the aged group. Aging induced down-regulation of PKA/BKCa pathway in cerebral artery in rats. The results provides new information on further understanding in cerebrovascular diseases resulted from age-related cerebral vascular dysfunction.

Methamphetamine use during the first or second half of pregnancy worsens cardiac ischemic injury in adult female offspring

There is growing evidence that methamphetamine use during pregnancy may produce detrimental cardiovascular effects in the adult offspring. Prior work demonstrated that chronic methamphetamine exposure throughout the gestational period causes adult female offspring to become hypersensitive to myocardial ischemic injury. The goal of the present study was to determine whether this methamphetamine-induced effect occurs early or late in the gestational period. Pregnant female rats were divided into 4 experimental groups. Groups 1 and 2 received subcutaneous injections of saline (group 1) or methamphetamine (5 mg/kg) (group 2) throughout the gestational period. Group 3 received methamphetamine injections on days 1-11 and saline on days 12-22, and group 4 received saline on days 1-11 and methamphetamine on days 12-22. Hearts were isolated from adult (8 weeks) female offspring and subjected to 30 min ischemia and 2 hours reperfusion on a Langendorff isolated heart apparatus. Contractile function was measured via an intraventricular balloon, and infarct size was measured by triphenyltetrazolium chloride staining. Infarcts were significantly larger in methamphetamine exposed offspring regardless of whether they had been exposed to methamphetamine during the first half or the second half of the gestational period. Prenatal exposure to methamphetamine had no effect on preischemic contractile function or postischemic recovery of contractile function. These data indicate that methamphetamine use during either the first half or second half of pregnancy increases susceptibility to myocardial infarction in adult female offspring. These data provide further evidence that prenatal exposure to methamphetamine may increase the risk of developing cardiovascular diseases during adulthood.

Prenatal Exposure to Methamphetamine Causes Vascular Dysfunction in Adult Male Rat Offspring

Methamphetamine use during pregnancy can have negative consequences on the offspring. However, most studies investigating the impact of prenatal exposure to methamphetamine have focused on behavioral and neurological outcomes. Relatively little is known regarding the impact of prenatal methamphetamine on the adult cardiovascular system. This study investigated the impact of chronic fetal exposure to methamphetamine on vascular function in adult offspring. Pregnant female rats received daily saline or methamphetamine (5 mg/kg) injections starting on gestational day 1 and continuing until the pups were born. Vascular function was assessed in 5 month old offspring. Prenatal methamphetamine significantly decreased both the efficacy and potency of acetylcholine-induced relaxation in isolated male (but not female) aortas when perivascular adipose tissue (PVAT) remained intact. However, prenatal methamphetamine had no impact on acetylcholine-induced relaxation when PVAT was removed. Nitroprusside-induced relaxation of the aorta was unaffected by prenatal methamphetamine. Angiotensin II-induced contractile responses were significantly potentiated in male (but not female) aortas regardless of the presence of PVAT. This effect was reversed by L-nitro arginine methyl ester (L-NAME). Serotonin- and phenylephrine-induced contraction were unaffected by prenatal methamphetamine. Prenatal methamphetamine had no impact on acetylcholine-induced relaxation of third order mesenteric arteries and no effect on basal blood pressure. These data provide evidence that prenatal exposure to methamphetamine sex-dependently alters vasomotor function in the vasculature and may increase the risk of developing vascular disorders later in adult life.

Rosacea pathogenesis, common triggers, and dietary role: The cause, the trigger, and the positive effects of different foods

Rosacea is a common chronic inflammatory cutaneous disorder, primarily manifesting on the cheeks, nose, chin, and forehead with a classic relapsing-remitting course that affects mostly fair skin types (Fitzpatrick I and II). The pathogenesis remains unclear, but the complex interplay between environmental and genetic factors may augment the innate immune response and neurovascular dysregulation. Different nutrients may play a role in the pathogenesis of rosacea. Many dietary triggers, including hot beverages, alcohol, spicy foods, caffeine, vanilla, cinnamon, niacin, marinated meats, and dairy products, have been postulated for this disease; however, there is a lack of well-designed and controlled studies evaluating the causal relationship between rosacea and dietary factors. We have explored the available evidence and hypotheses based on trigger-food categories of rosacea, the role of the skin-gut microbiome axis, and potentially benefiting dietary factors such as probiotics, prebiotics, and high-fiber diets.

Prenatal exercise reprograms the development of hypertension progress and improves vascular health in SHR offspring

BACKGROUND

Upregulation of L-type voltage-gated Ca²⁺ (Ca_V1.2) channel in the arterial myocytes is a hallmark feature of hypertension. However, whether maternal exercise during pregnancy has a sustained beneficial effect on the offspring of spontaneously hypertensive rats (SHRs) through epigenetic regulation of Ca_V1.2 channel is largely unknown.

METHODS

Pregnant SHRs and Wistar-Kyoto rats were subjected to swimming and the vascular molecular and functional properties of male offspring were evaluated at embryonic (E) 20.5 day, 3 months (3 M), and 6 months (6 M).

RESULTS

Exercise during pregnancy significantly decreased the resting blood pressure at 3 M but not 6 M in the offspring of SHR. Prenatal exercise significantly reduced the cardiovascular reactivity, the contribution of Ca_V1.2 channel to the vascular tone, and the whole-cell current density of Ca_V1.2 channel in both 3 M and 6 M offspring of SHR. Moreover, maternal exercise triggered hypermethylation of the promoter region of the Ca_V1.2 α1C gene (CACNA1C), with a concomitant decrease in its protein and mRNA expressions in SHR offspring at E20.5, 3 M, and 6 M. Tissue culture experiments further confirmed that 5-Aza-2'-deoxycytidine increased the structure and functional expression of Ca_V1.2 channel by inhibiting the DNA methylation of CACNA1C. However, the improvement of prenatal exercise on the blood pressure, function, and expression of Ca_V1.2 channel was attenuated in the offspring of SHRs at 6 M compared to the 3 M readout.

CONCLUSIONS

These data suggest that prenatal exercise improves the vascular function by the hypermethylation of CACNA1C in the arterial myocytes and delays the development of hypertension in the offspring of SHRs. However, these effects fade out with age.

Antenatal Hypoxia Affects Pulmonary Artery Contractile Functions via Downregulating L-type Ca2+ Channels Subunit Alpha1 C in Adult Male Offspring

Background

Antenatal intrauterine fetal hypoxia is a common pregnancy complication that has profound adverse effects on an individual's vascular health later in life. Pulmonary arteries are sensitive to hypoxia, but adverse effects of antenatal hypoxia on pulmonary vasoreactivities in the offspring remain unknown. This study aimed to determine the effects and related mechanisms of antenatal hypoxia on pulmonary artery functions in adult male offspring.

Methods and Results

Pregnant Sprague‐Dawley rats were housed in a normoxic or hypoxic (10.5% O₂) chamber from gestation days 10 to 20. Male offspring were euthanized at 16 weeks old (adult offspring). Pulmonary arteries were collected for vascular function, electrophysiology, target gene expression, and promoter methylation studies. In pulmonary artery rings, contractions to serotonin hydrochloride, angiotensin II, or phenylephrine were reduced in the antenatal hypoxic offspring, which resulted from inactivated L‐type Ca²⁺ channels. In pulmonary artery smooth muscle cells, the basal whole‐cell Ca²⁺ currents, as well as vasoconstrictor‐induced Ca²⁺ transients were significantly reduced in antenatal hypoxic offspring. In addition, increased promoter methylations within L‐type Ca²⁺ channel subunit alpha1 C were compatible with its reduced expressions.

Conclusions

This study indicated that antenatal hypoxia programmed long‐lasting vascular hypocontractility in the male offspring that is linked to decreases of L‐type Ca²⁺ channel subunit alpha1 C in the pulmonary arteries. Antenatal hypoxia resulted in pulmonary artery adverse outcomes in postnatal offspring, was strongly associated with reprogrammed L‐type Ca²⁺ channel subunit alpha1 C expression via a DNA methylation‐mediated epigenetic mechanism, advancing understanding toward the effect of antenatal hypoxia in early life on long‐term vascular health.

Does Prenatal Exposure to CNS Stimulants Increase the Risk of Cardiovascular Disease in Adult Offspring?

Prenatal exposure to an adverse uterine environment can have long lasting effects on adult offspring through DNA methylation, histone acetylation, and other epigenetic effects that alter gene expression and physiology. It is well-known that consumption of CNS stimulants such as caffeine, nicotine, amphetamines, and cocaine during pregnancy can adversely impact the offspring. However, most work in this area has focused on neurological and behavioral outcomes and has been limited to assessments in young offspring. The impact of prenatal exposure to these agents on the adult cardiovascular system has received relatively little attention. Evidence from both animal and human studies indicate that exposure to CNS stimulants during the gestational period can negatively impact the adult heart and vasculature, potentially leading to cardiovascular diseases later in life. This review discusses our current understanding of the impact of prenatal exposure to cocaine, methamphetamine, nicotine, and caffeine on the adult cardiovascular system.

DNA Methylation-Reprogrammed Ang II (Angiotensin II) Type 1 Receptor-Early Growth Response Gene 1-Protein Kinase C ε Axis Underlies Vascular Hypercontractility in Antenatal Hypoxic Offspring

As the most common clinical stress during mid and late pregnancy, antenatal hypoxia has profound adverse effects on individual's vascular health later in life, but the underlying mechanisms are still not understood. The purpose of this study was to reveal the mechanisms of the acquired vascular dysfunction in offspring imposed by antenatal hypoxia. Pregnant rats were housed in a normoxic or hypoxic (10.5% oxygen) chamber from gestation day 10 to 21. Male offspring were euthanized at gestational day 21 (fetus) or postnatal 16 weeks old (adult offspring). Mesenteric arteries were collected for examining Ang II (angiotensin II)-mediated vascular contractility, gene expression, and promoter methylation. Antenatal hypoxia increased vascular sensitivity to Ang II, which was resulted by an upregulated AT1R (angiotensin II type 1 receptor). The increased AT1R was correlated with a hypomethylation-mediated activated transcription of Agtr1a (alpha subtype of AT1R). In addition, we presented evidences that there was an AT1R-Egr1 (early growth response gene 1)-PKCε (ε isoform of protein kinase C) axis in vasculature; AT1R could modulate PKCε expression via upregulating Egr1; Egr1 mediated transcription activation of PKCε via Egr1 binding sites in PKCε gene promoter. Overall, antenatal hypoxia activated AT1R-Egr1-PKCε axis in vasculature, eventually predisposed offspring to vascular hypercontractility. This is the first description that antenatal hypoxia resulted in vascular adverse outcomes in postnatal offspring, was strongly associated with reprogrammed gene expression via a DNA methylation-mediated epigenetic mechanism, advancing understanding toward the influence of adverse antenatal factors in early life on long-term vascular health.

Antenatal Dexamethasone Exposure Impairs the High-Conductance Ca2+-Activated K+ Channels via Epigenetic Alteration at Gene Promoter in Male Offspring

OBJECTIVE

Antenatal exposure to glucocorticoids increases cardiovascular risks related to vascular dysfunctions in offspring, although underlying mechanisms are still unknown. As an important vascular mediator, high-conductance Ca²⁺-activated K⁺ channels (BK) plays an essential role in determining vascular tone. Long-term effects of antenatal glucocorticoids on BK in offspring are largely unknown. This study examined the effects and mechanisms of antenatal exposure to clinically relevant doses of glucocorticoids on vascular BK in offspring. Approach and Results: Pregnant Sprague-Dawley rats received synthetic glucocorticoids dexamethasone or vehicle during the last week of pregnancy. Vascular functions, cellular electrophysiology, target gene expression, and promoter methylation were examined in mesenteric arteries of male offspring (gestational day 21 [fetus] and postnatal day 120 [adult offspring]). Antenatal dexamethasone exposure impaired BK activators-mediated relaxation and reduced whole-cell BK currents in mesenteric arteries. Antenatal dexamethasone exposure did not alter Ca²⁺/voltage-sensitivity of BK but downregulated the expressions of BK α and β1 subunits in both fetal and adult mesenteric arteries. In addition, increased promoter methylations within BKα and BKβ1 were compatible with reduced expressions of the 2 genes.

CONCLUSIONS

Our findings showed a profound and long-term impact of antenatal dexamethasone exposure on vascular BK via an altered epigenetic pattern from fetal stage to adulthood, advancing understanding of prolonged adverse effects and mechanisms of antenatal glucocorticoids exposure on vascular health in offspring.

Sarcoplasmic reticulum and calcium signaling in muscle cells: Homeostasis and disease

The sarco/endoplasmic reticulum is an extensive, dynamic and heterogeneous membranous network that fulfills multiple homeostatic functions. Among them, it compartmentalizes, stores and releases calcium within the intracellular space. In the case of muscle cells, calcium released from the sarco/endoplasmic reticulum in the vicinity of the contractile machinery induces cell contraction. Furthermore, sarco/endoplasmic reticulum-derived calcium also regulates gene transcription in the nucleus, energy metabolism in mitochondria and cytosolic signaling pathways. These diverse and overlapping processes require a highly complex fine-tuning that the sarco/endoplasmic reticulum provides by means of its numerous tubules and cisternae, specialized domains and contacts with other organelles. The sarco/endoplasmic reticulum also possesses a rich calcium-handling machinery, functionally coupled to both contraction-inducing stimuli and the contractile apparatus. Such is the importance of the sarco/endoplasmic reticulum for muscle cell physiology, that alterations in its structure, function or its calcium-handling machinery are intimately associated with the development of cardiometabolic diseases. Cardiac hypertrophy, insulin resistance and arterial hypertension are age-related pathologies with a common mechanism at the muscle cell level: the accumulation of damaged proteins at the sarco/endoplasmic reticulum induces a stress response condition termed endoplasmic reticulum stress, which impairs proper organelle function, ultimately leading to pathogenesis.

Association of Caffeine Intake and Caffeinated Coffee Consumption With Risk of Incident Rosacea in Women

Importance

Caffeine is known to decrease vasodilation and have immunosuppressant effects, which may potentially decrease the risk of rosacea. However, the heat from coffee may be a trigger for rosacea flares. The relationship between the risk of rosacea and caffeine intake, including coffee consumption, is poorly understood.

Objective

To determine the association between the risk of incident rosacea and caffeine intake, including coffee consumption.

Design, Setting, and Participants

This cohort study included 82 737 women in the Nurses' Health Study II (NHS II), a prospective cohort established in 1989, with follow-up conducted biennially between 1991 and 2005. All analysis took place between June 2017 and June 2018.

Exposures

Data on coffee, tea, soda, and chocolate consumption were collected every 4 years during follow-up.

Main Outcomes and Measures

Information on history of clinician-diagnosed rosacea and year of diagnosis was collected in 2005.

Results

A total of 82 737 women responded to the question regarding a diagnosis of rosacea in 2005 in NHS II and were included in the final analysis (mean [SD] age at study entry, 50.5 [4.6] years). During 1 120 051 person-years of follow-up, we identified 4945 incident cases of rosacea. After adjustment for other risk factors, we found an inverse association between increased caffeine intake and risk of rosacea (hazard ratio for the highest quintile of caffeine intake vs the lowest, 0.76; 95% CI, 0.69-0.84; P < .001 for trend). A significant inverse association with risk of rosacea was also observed for caffeinated coffee consumption (HR, 0.77 for those who consumed ≥4 servings/d vs those who consumed <1/mo; 95% CI, 0.69-0.87; P < .001 for trend), but not for decaffeinated coffee (HR, 0.80; 95% CI, 0.56-1.14; P = .39 for trend). Further analyses found that increased caffeine intake from foods other than coffee (tea, soda, and chocolate) was not significantly associated with decreased risk of rosacea.

Conclusions and Relevance

Increased caffeine intake from coffee was inversely associated with the risk of incident rosacea. Our findings do not support limiting caffeine intake as a means to prevent rosacea. Further studies are required to explain the mechanisms of action of these associations, to replicate our findings in other populations, and to explore the relationship of caffeine with different rosacea subtypes.

Prenatal caffeine damaged learning and memory in rat offspring mediated by ARs/PKA/CREB/BDNF pathway

Prenatal exposure to caffeine can cause developmental problems. This study determined chronic influence of prenatal caffeine at relatively higher doses on cognitive functions in the rat offspring. Pregnant Sprague-Dawley rats (4-month-old) were exposed to caffeine (20 mg/kg, twice a day) for whole pregnancy from gestational day 4. Fetal and offspring body and brain weight was measured. Learning and memory were tested in adult offspring with Morris water maze. Learning and memory-related receptors were measured. The exposure to prenatal caffeine not only caused fetal growth restriction, but also showed long-term effects on learning and memory in the offspring. The caffeine offspring exhibited longer escape latency and path length in navigation testing. The number of passing the target was significantly reduced in those offspring. The expression of adenosine A(1) and A(2A) receptors, nuclear PKA C(alpha), C(beta) subunits, and pCREB were significantly increased in the fetal and neonatal brain, and suppressed in the hippocampus of the adult offspring. The expression of BDNF and TrkB were reduced regardless of various ages. The results suggest that intrauterine programming dysfunction of adenosine receptors and the down-stream of cAMP/PKA/pCREB system may play an important role in prenatal caffeine induced cognition disorders in the adult offspring.

A novel mechanism of angiotensin II-regulated placental vascular tone in the development of hypertension in preeclampsia

The present study tested the hypothesis that angiotensin II plays a role in the regulation of placental vascular tone, which contributes to hypertension in preeclampsia. Functional and molecular assays were performed in large and micro placental and non-placental vessels from humans and animals. In human placental vessels, angiotensin II induced vasoconstrictions in 78.7% vessels in 155 tests, as referenced to KCl-induced contractions. In contrast, phenylephrine only produced contractions in 3.0% of 133 tests. In non-placental vessels, phenylephrine induced contractions in 76.0% of 67 tests, whereas angiotensin II failed to produce contractions in 75 tests. Similar results were obtained in animal placental and non-placental vessels. Compared with non-placental vessels, angiotensin II receptors and β -adrenoceptors were significantly increased in placental vessels. Compared to the vessels from normal pregnancy, angiotensin II-induced vasoconstrictions were significantly reduced in preeclamptic placentas, which was associated with a decrease in angiotensin II receptors. In addition, angiotensin II and angiotensin converting enzyme in the maternal-placenta circulation in preeclampsia were increased, whereas angiotensin I and angiotensin1-7 concentrations were unchanged. The study demonstrates a selective effect of angiotensin II in maintaining placental vessel tension, which may play an important role in development of hypertension in preeclampsia.

New conception for the development of hypertension in preeclampsia

Placental vascular dysfunction was suggested to be critical for placental ischemia-initiated hypertension in preeclampsia, although the contributions of endothelium involved are unclear. The present study found, unlike non-placental vessels, acetylcholine showed no vasodilatation effect on placental vessels, indicating that endothelial-derived nitric oxide (NO) was extremely weak in placental vessels. Placental vascular responses to exogenous NO from sodium nitroprusside (SNP) were significantly different from non-placental vessels. These results were further confirmed in sheep, and rat vessels. In preeclamptic placental vessels, acetylcholine also showed no vasodilatation effects, while vascular responses to SNP were suppressed, associated with impaired cGMP/sGC pathway in vascular smooth muscle cells (VSMCs). The current theory on placental ischemia-initiated hypertension in preeclampsia focused on changes in placental vascular functions, including endothelial dysfunction. This study found the placental endothelium contributed very poorly to vasodilatation, and altered vascular functions in preeclampsia mainly occurred in VSMCs instead of endothelial cells. The findings contribute importantly to understanding the special feature of placental vascular functions and its pathophysiological changes in the development of hypertension in preeclampsia.

Prenatal Hypoxia Induced Dysfunction in Cerebral Arteries of Offspring Rats

BACKGROUND

Hypoxia during pregnancy could cause abnormal development and lead to increased risks of vascular diseases in adults. This study determined angiotensin II (AII)-mediated vascular dysfunction in offspring middle cerebral arteries (MCA).

METHODS AND RESULTS

Pregnant rats were subjected to hypoxia. Vascular tension in offspring MCA by AII with or without inhibitors, calcium channel activities, and endoplasmic reticulum calcium stores were tested. Whole-cell patch clamping was used to investigate voltage-dependent calcium channel currents. mRNA expression was tested using quantitative real-time polymerase chain reaction. AII-mediated MCA constriction was greater in male offspring exposed to prenatal hypoxia. AT1 and AT2 receptors were involved in the altered AII-mediated vasoconstriction. Prenatal hypoxia increased baseline activities of L-type calcium channel currents in MCA smooth muscle cells. However, calcium currents stimulated by AII were not significantly changed, whereas nifedipine inhibited AII-mediated vasoconstrictions in the MCA. Activities of IP3/ryanodine receptor-operated calcium channels, endoplasmic reticulum calcium stores, and sarcoendoplasmic reticulum membrane Ca2+-ATPase were increased. Prenatal hypoxia also caused dysfunction of vasodilatation via the endothelium NO synthase. The mRNA expressions of AT1A, AT1B, AT2R, Cav1.2α1C, Cav3.2α1H, and ryanodine receptor RyR2 were increased in the prenatal-hypoxia group.

CONCLUSIONS

Hypoxia in pregnancy could induce dysfunction in both contraction and dilation in the offspring MCA. AII-increased constriction in the prenatal-hypoxia group was not mainly dependent on the L-type and T-type calcium channels; it might predominantly rely on the AII receptors, IP3/ryanodine receptors, and the endoplasmic reticulum calcium store as well as calcium ATPase.

Regulation of cerebral arterial BKCa channels by angiotensin II signaling in adult offspring exposed to prenatal high sucrose diets

Prenatal insults have been shown to affect vascular functions, leading to increased risks of cardiovascular diseases in offspring. The present study determined whether high sucrose (HS) intake in pregnancy affected central vascular functions in middle cerebral artery (MCA) of offspring. Sprague-Dawley rats were fed a standard food and tap water with normal or high (20%) sucrose content during pregnancy. Offspring were maintained with normal diets and tap water. Central vascular functions and related ion channels were assessed in male offspring at 5 months old. Compared with the control, angiotensin II (AII)-induced vasoconstrictions were significantly higher in the MCA of the offspring exposed to prenatal HS. In the MCA, large conductance Ca²⁺-activated K⁺ channels (BKCa) currents were decreased with a reduction of opening frequency, sensitivity to intracellular Ca²⁺/membrane voltage, and BKβ1 expression. mRNA levels of AT1α and AT2, as well as AT1/AT2 ratio, were significantly increased in the MCA of offspring following exposure to prenatal HS diets. The data suggested that prenatal HS diets could alter microvascular activities in the MCA, probably via changes of BKCa channels in the brain.

Smooth Muscle Ion Channels and Regulation of Vascular Tone in Resistance Arteries and Arterioles

Vascular tone of resistance arteries and arterioles determines peripheral vascular resistance, contributing to the regulation of blood pressure and blood flow to, and within the body's tissues and organs. Ion channels in the plasma membrane and endoplasmic reticulum of vascular smooth muscle cells (SMCs) in these blood vessels importantly contribute to the regulation of intracellular Ca2+ concentration, the primary determinant of SMC contractile activity and vascular tone. Ion channels provide the main source of activator Ca2+ that determines vascular tone, and strongly contribute to setting and regulating membrane potential, which, in turn, regulates the open-state-probability of voltage gated Ca2+ channels (VGCCs), the primary source of Ca2+ in resistance artery and arteriolar SMCs. Ion channel function is also modulated by vasoconstrictors and vasodilators, contributing to all aspects of the regulation of vascular tone. This review will focus on the physiology of VGCCs, voltage-gated K+ (KV) channels, large-conductance Ca2+-activated K+ (BKCa) channels, strong-inward-rectifier K+ (KIR) channels, ATP-sensitive K+ (KATP) channels, ryanodine receptors (RyRs), inositol 1,4,5-trisphosphate receptors (IP3Rs), and a variety of transient receptor potential (TRP) channels that contribute to pressure-induced myogenic tone in resistance arteries and arterioles, the modulation of the function of these ion channels by vasoconstrictors and vasodilators, their role in the functional regulation of tissue blood flow and their dysfunction in diseases such as hypertension, obesity, and diabetes. © 2017 American Physiological Society. Compr Physiol 7:485-581, 2017.