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Roysommuti S, Malila P, Lerdweeraphon W, Jirakulsomchok D, Wyss JM. Perinatal taurine exposure alters renal potassium excretion mechanisms in adult conscious rats. J Biomed Sci 2010; 17 Suppl 1:S29. [PMID: 20804604 PMCID: PMC2994394 DOI: 10.1186/1423-0127-17-s1-s29] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Perinatal taurine exposure has long-term effects on the arterial pressure and renal function. This study tests its influence on renal potassium excretion in young adult, conscious rats. Female Sprague-Dawley rats were fed normal rat chow and given water alone (C), 3% beta-alanine in water (taurine depletion, TD) or 3% taurine in water (taurine supplementation, TS), either from conception until delivery (fetal period; TDF or TSF) or from delivery until weaning (lactation period; TDL or TSL). In Experiment 1, male offspring were fed normal rat chow and tap water, while in Experiment 2, beta-alanine and taurine were treated from conception until weaning and then female pups were fed normal rat chow and 5% glucose in drinking water (CG, TDG or TSG) or water alone (CW, TDW or TSW). At 7-8 weeks of age, renal potassium excretion was measured at rest and after an acute saline load (5% of body weight) in conscious, restrained rats. Although all male groups displayed similar renal potassium excretion, TSF rats slightly increased fractional potassium excretion at rest but not in response to saline load, whereas TDF did the opposite. Plasma potassium concentration was only slightly altered by the diet manipulations. In female offspring, none of the perinatal treatments significantly altered renal potassium excretion at rest or after saline load. High sugar intake slightly decreased potassium excretion at rest in TDG and TSG, but only the TDG group displayed a decreased response to saline load. The present data indicates that perinatal taurine exposure only mildly influences renal potassium excretion in adult male and female rats.
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Affiliation(s)
- Sanya Roysommuti
- Department of Physiology, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand.
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Abstract
Hypertension and type 2 diabetes mellitus (T2DM) are powerful risk factors for cardiovascular disease (CVD) and chronic kidney disease (CKD), both of which are leading causes of morbidity and mortality worldwide. Research into the pathophysiology of CVD and CKD risk factors has identified salt sensitivity and insulin resistance as key elements underlying the relationship between hypertension and T2DM. Excess dietary salt and caloric intake, as commonly found in westernized diets, is linked not only to increased blood pressure, but also to defective insulin sensitivity and impaired glucose homeostasis. In this setting, activation of the sympathetic nervous system and the renin-angiotensin-aldosterone system (RAAS), as well as increased signaling through the mineralocorticoid receptor (MR), result in increased production of reactive oxygen species and oxidative stress, which in turn contribute to insulin resistance and impaired vascular function. In addition, insulin resistance is not limited to classic insulin-sensitive tissues such as skeletal muscle, but it also affects the cardiovascular system, where it participates in the development of CVD and CKD. Current clinical knowledge points towards an impact of salt restriction, RAAS blockade, and MR antagonism on cardiovascular and renal protection, but also on improved insulin sensitivity and glucose homeostasis.
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NKCC1 and hypertension: a novel therapeutic target involved in the regulation of vascular tone and renal function. Curr Opin Nephrol Hypertens 2010; 19:163-8. [PMID: 20061948 DOI: 10.1097/mnh.0b013e3283360a46] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
PURPOSE OF REVIEW The present review summarizes recent advances in our understanding of the mechanisms involving the housekeeping Na+, K+, 2Cl(-) cotransporter (NKCC1) in blood pressure (BP) regulation. RECENT FINDINGS High-ceiling diuretics (HCDs), known potent inhibitors of NKCC1, renal-specific NKCC2 and four isoforms of K+, Cl(-) cotransporters decrease [Cl(-)]i, hyperpolarize vascular smooth muscle cells and suppress myogenic tone and contractions evoked by modest depolarization, phenylephrine, angiotensin II and uridine triphosphate. These actions are absent in NKCC1(-/-) mice, indicating that HCDs interact with NKCC1 rather than with other potential targets. NKCC1-null mice have decreased baseline BP but exhibit augmented BP increment evoked by high-salt diets. NKCC1 deficiency causes approximately three-fold elevation in plasma renin concentrations and attenuates HCD-induced renin production. In addition to HCDs, NKCC1 is also inhibited by extracellular HCO3(-) in the range corresponding to its concentration in ischemic extracellular fluids. SUMMARY NKCC1 modulates BP through vascular and renal effects. In addition to BP regulation, the decreased baseline activity of this carrier or its suppression by chronic treatment with HCDs may lead to inhibition of myogenic tone and progression of end-stage renal disease. NKCC1 activation in ischemia-induced acidosis may contribute to stroke via glutamate release caused by astrocyte swelling.
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Gao F, Wang DH. Impairment in function and expression of transient receptor potential vanilloid type 4 in Dahl salt-sensitive rats: significance and mechanism. Hypertension 2010; 55:1018-25. [PMID: 20194297 PMCID: PMC2862636 DOI: 10.1161/hypertensionaha.109.147710] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
To examine the role of transient receptor potential vanilloid type 4 (TRPV4) channels in the development of salt-sensitive hypertension, male Dahl salt-sensitive (DS) and -resistant (DR) rats were fed a low-salt (LS) or high-salt (HS) diet for 3 weeks. DS-HS but not DR-HS rats developed hypertension. 4alpha-Phorbol-12,13-didecanoate (a selective TRPV4 activator; 2.5 mg/kg IV) decreased mean arterial pressure in all of the groups with the greatest effects in DR-HS and the least in DS-HS rats (P<0.05). Depressor effects of 4alpha-phorbol-12,13-didecanoate but not dihydrocapsaicin (a selective TRPV1 agonist; 30 microg/kg IV) were abolished by ruthenium red (a TRPV4 antagonist; 3 mg/kg IV) in all of the groups. Blockade of TRPV4 with ruthenium red increased mean arterial pressure in DR-HS rats only (P<0.05). TRPV4 protein contents were decreased in the renal cortex, medulla, and dorsal root ganglia in DS-HS compared with DS-LS rats but increased in dorsal root ganglia and mesenteric arteries in DR-HS compared with DR-LS rats (P<0.05). Mean arterial pressure responses to blockade of small- and large-/intermediate-conductance Ca(2+)-activated K(+) channels (Maxikappa channels) with apamin and charybdotoxin, respectively, were examined. Apamin (100 microg/kg) plus charybdotoxin (100 microg/kg) abolished 4alpha-phorbol-12,13-didecanoate-induced hypotension in DR-LS, DR-HS, and DS-LS rats only. Thus, HS-induced enhancement of TRPV4 function and expression in sensory neurons and resistant vessels in DR rats may prevent salt-induced hypertension possibly via activation of Maxikappa channels given that blockade of TRPV4 elevates mean arterial pressure. In contrast, HS-induced suppression of TRPV4 function and expression in sensory neurons and kidneys in DS rats may contribute to increased salt sensitivity.
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Affiliation(s)
- Feng Gao
- Department of Medicine, Michigan State University, Michigan
| | - Donna H. Wang
- Department of Medicine, Michigan State University, Michigan
- Neuroscience Program, Michigan State University, Michigan
- Cell and Molecular Biology Program, Michigan State University, Michigan
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Fedorova OV, Shapiro JI, Bagrov AY. Endogenous cardiotonic steroids and salt-sensitive hypertension. Biochim Biophys Acta Mol Basis Dis 2010; 1802:1230-6. [PMID: 20347967 DOI: 10.1016/j.bbadis.2010.03.011] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2010] [Revised: 03/18/2010] [Accepted: 03/20/2010] [Indexed: 12/12/2022]
Abstract
Endogenous cardiotonic steroids (CTS), also called digitalis like factors, have been postulated to play important roles in pathogenesis of hypertension for nearly half of a century. For the past 50 years biomedical scientists have been in quest of an unidentified factor or hormone that both increases blood pressure and renal sodium excretion; this "natriuretic hormone" was, in fact, postulated to interact with the Na/K-ATPase. Recent discoveries have led to the identification of steroid molecules which are present in humans, rodents and amphibians, and which, in a complex manner, interact with each other and with the other systems that regulate renal salt handling and contribute to the salt-sensitivity of blood pressure. Recent findings include the specific identification of endogenous cardenolide (endogenous ouabain) and bufadienolide (marinobufagenin) CTS in humans along with the delineation of mechanisms by which CTS can signal through the Na/K-ATPase. Although CTS were first considered important in the regulation of renal sodium transport and arterial pressure, more recent work implicates these hormones in the central regulation of blood pressure and regulation of cell growth, and development of cardiovascular and renal fibrosis in particular.
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Affiliation(s)
- Olga V Fedorova
- National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
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Selective chloride loading is pressor in the stroke-prone spontaneously hypertensive rat despite hydrochlorothiazide-induced natriuresis. J Hypertens 2010; 28:87-94. [PMID: 19851120 DOI: 10.1097/hjh.0b013e3283316cfc] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
OBJECTIVE To test the hypothesis that in the stroke-prone spontaneously hypertensive rat (SHRSP), the pressor effect of selective dietary chloride loading depends on a positive external sodium balance. METHODS In 43 male SHRSP fed a Japanese style diet containing a low normal amount of NaCl (0.4%), we compared the effects on telemetrically measured SBP of hydrochlorothiazide, 25 mg/kg per day, alone ('TZ', n = 11); hydrochlorothiazide combined with either KCl ('KCLTZ', 2%K, n = 10) or KHCO3 ('KBCTZ', 2%K, n = 11) and no hydrochlorothiazide ('CTL', n = 11) over a 10-week period starting at 10 weeks of age. RESULTS With either TZ or KBCTZ, SBP did not increase above baseline values. However, KCLTZ induced a sustained increase in SBP of 17 mmHg (P < 0.0001), an increase almost half of that occurring without hydrochlorothiazide (CTL), 38 mmHg (P < 0.0001). Such divergence of blood pressures with KCLTZ and KBCTZ began over the first 3 days of their administration, even while they induced similarly negative external sodium balances, a positive one occurring only in CTL. Body weight increased more without, than with, hydrochlorothiazide, but did not differ between KCLTZ and KBCTZ. Changes in SBP occurring on day 2 after treatment assignment predicted final changes. CONCLUSION These results demonstrate that in the SHRSP, dietary KCl loading can induce a pressor effect despite concomitant hydrochlorothiazide-induced natriuresis that elicits a negative external sodium balance. The results provide evidence that in the SHRSP the pressor effect of selective chloride loading does not depend on a positive external sodium balance, but rather on a mechanism actuated by chloride per se.
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Reduced nephron endowment due to fetal uninephrectomy impairs renal sodium handling in male sheep. Clin Sci (Lond) 2010; 118:669-80. [PMID: 20067444 DOI: 10.1042/cs20090479] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Reduced nephron endowment is associated with development of renal and cardiovascular disease. We hypothesized this may be attributable to impaired sodium homoeostasis by the remaining nephrons. The present study investigated whether a nephron deficit, induced by fetal uninephrectomy at 100 days gestation (term=150 days), resulted in (i) altered renal sodium handling both under basal conditions and in response to an acute 0.9% saline load (50 ml.kg-1 of body weight.30 min-1); (ii) hypertension and (iii) altered expression of renal channels/transporters in male sheep at 6 months of age. Uninephrectomized animals had significantly elevated arterial pressure (90.1+/-1.6 compared with 77.8+/-2.9 mmHg; P<0.001), while glomerular filtration rate and renal blood flow (per g of kidney weight) were 30% lower than that of the sham animals. Total kidney weight was similar between the groups. Renal gene expression of apical NHE3 (type 3 Na+/H+ exchanger), ENaC (epithelium Na+ channel) beta and gamma subunits and basolateral Na+/K+ ATPase beta and gamma subunits were significantly elevated in uninephrectomized animals, while ENaC alpha subunit expression was reduced. Urine flow rate and sodium excretion increased in both groups in response to salt loading, but this increase in sodium excretion was delayed by approximately 90 min in the uninephrectomized animals, while total sodium output was 12% in excess of the infused load (P<0.05). In conclusion, the present study shows that animals with a congenital nephron deficit have alterations in tubular sodium channels/transporters and cannot rapidly correct for variations in sodium intake probably contributing to the development of hypertension. This suggests that people born with a nephron deficit should be monitored for early signs of renal and cardiovascular disease.
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Perez-Rojas JM, Kassem KM, Beierwaltes WH, Garvin JL, Herrera M. Nitric oxide produced by endothelial nitric oxide synthase promotes diuresis. Am J Physiol Regul Integr Comp Physiol 2010; 298:R1050-5. [PMID: 20147612 DOI: 10.1152/ajpregu.00181.2009] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Extracellular fluid volume is highly regulated, at least in part, by peripheral resistance and renal function. Nitric oxide (NO) produced by NO synthase type 3 (NOS 3) in the nonrenal vasculature may promote fluid retention by reducing systemic vascular resistance and arterial pressure. In contrast, NO produced by renal NOS 3 promotes water excretion by reducing renal vascular resistance, increasing glomerular filtration, and inhibiting reabsorption along the nephron. Thus, the net effect of NO from NOS 3 on urinary volume (UV) is unclear. We hypothesized that NO produced by NOS 3 promotes water excretion primarily due to renal tubular effects. We gave conscious wild-type and NOS 3 -/- mice an acute volume load and measured UV, blood pressure, plasma renin concentration (PRC), Na(+), vasopressin, and urinary Na(+) and creatinine concentrations. To give the acute volume load, we trained mice to drink a large volume of water while in metabolic cages. On the day of the experiment, water was replaced with 1% sucrose, and mice had access to it for 1 h. Volume intake was similar in both groups. Over 3 h, wild-type mice excreted 62 +/- 10% of the volume load, but NOS 3 -/- excreted only 42 +/- 5% (P < 0.05). Blood pressure in NOS 3 -/- was 118 +/- 3 compared with 110 +/- 2 mmHg in wild-type mice (P < 0.05), but it did not change following volume load in either strain. PRC, vasopressin, and glomerular filtration rate were similar between groups. Urinary Na(+) excretion was 49.3 +/- 7.0 in wild-type vs. 37.8 +/- 6.4 mumol/3 h in NOS 3 -/- mice (P < 0.05). Bumetanide administration eliminated the difference in volume excretion between wild-type and NOS 3 -/- mice. We conclude that 1) NO produced by NOS 3 promotes water and Na(+) excretion and 2) the renal epithelial actions of NO produced by NOS 3 supersede the systemic and renal vascular actions.
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Affiliation(s)
- Jazmin M Perez-Rojas
- Division of Hypertension and Vascular Research, Henry Ford Hospital, Detroit, MI 48202, USA
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Harrington MG, Salomon RM, Pogoda JM, Oborina E, Okey N, Johnson B, Schmidt D, Fonteh AN, Dalleska NF. Cerebrospinal fluid sodium rhythms. Cerebrospinal Fluid Res 2010; 7:3. [PMID: 20205754 PMCID: PMC2822736 DOI: 10.1186/1743-8454-7-3] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2009] [Accepted: 01/20/2010] [Indexed: 11/23/2022] Open
Abstract
Background Cerebrospinal fluid (CSF) sodium levels have been reported to rise during episodic migraine. Since migraine frequently starts in early morning or late afternoon, we hypothesized that natural sodium chronobiology may predispose susceptible persons when extracellular CSF sodium increases. Since no mammalian brain sodium rhythms are known, we designed a study of healthy humans to test if cation rhythms exist in CSF. Methods Lumbar CSF was collected every ten minutes at 0.1 mL/min for 24 h from six healthy participants. CSF sodium and potassium concentrations were measured by ion chromatography, total protein by fluorescent spectrometry, and osmolarity by freezing point depression. We analyzed cation and protein distributions over the 24 h period and spectral and permutation tests to identify significant rhythms. We applied the False Discovery Rate method to adjust significance levels for multiple tests and Spearman correlations to compare sodium fluctuations with potassium, protein, and osmolarity. Results The distribution of sodium varied much more than potassium, and there were statistically significant rhythms at 12 and 1.65 h periods. Curve fitting to the average time course of the mean sodium of all six subjects revealed the lowest sodium levels at 03.20 h and highest at 08.00 h, a second nadir at 09.50 h and a second peak at 18.10 h. Sodium levels were not correlated with potassium or protein concentration, or with osmolarity. Conclusion These CSF rhythms are the first reports of sodium chronobiology in the human nervous system. The results are consistent with our hypothesis that rising levels of extracellular sodium may contribute to the timing of migraine onset. The physiological importance of sodium in the nervous system suggests that these rhythms may have additional repercussions on ultradian functions.
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Kolaj M, Renaud LP. Metabotropic glutamate receptors in median preoptic neurons modulate neuronal excitability and glutamatergic and GABAergic inputs from the subfornical organ. J Neurophysiol 2009; 103:1104-13. [PMID: 20018832 DOI: 10.1152/jn.00808.2009] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Cardiovascular and behavioral responses to circulating angiotensin require intact connectivity along the upper lamina terminalis joining the subfornical organ (SFO) with the median preoptic nucleus (MnPO). In the present study on MnPO neurons, we used whole cell patch-clamp recording techniques in brain slice preparations to evaluate the influence of metabotropic glutamate receptor (mGluR) agonists on modulating their intrinsic excitability and SFO-evoked glutamatergic and GABAergic postsynaptic currents. In 22/36 cells, bath application of a mGluR group I agonist (S)-3,5-dihydroxyphenylglycine (DHPG) induced a TTX-resistant inward current coupled with decrease in a membrane K(+) conductance but also a possible increase in a nonselective cationic conductance. By contrast, 27/49 cells responded to a mGluR group II agonist (2S,2'R,3'R)-2-(2',3'-dicarboxycyclopropyl)glycine (DCG IV) with a TTX-resistant outward current and increase in membrane conductance that reversed around -95 mV, suggesting opening of K(+) channels. None of 19 cells responded to the mGluR group III agonist l-(+)-2-amino-4-phosphonobutyric acid (l-AP4). Agonists for all mGluR groups suppressed SFO-evoked excitatory postsynaptic currents and significantly increased paired-pulse ratios, implying a presynaptic mechanism. Only the mGluR group II agonist significantly reduced SFO-evoked inhibitory postsynaptic currents and caused an increase in paired-pulse ratios. These results suggest a complexity of pre- and postsynaptic mGluRs are available to modulate rapid neurotransmission along the upper lamina terminalis from SFO to MnPO.
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Affiliation(s)
- Miloslav Kolaj
- Neuroscience Program, Ottawa Hospital Research Institute and University of Ottawa, Ottawa, Ontario K1Y 4E9, Canada.
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Wang X, Armando I, Upadhyay K, Pascua A, Jose PA. The regulation of proximal tubular salt transport in hypertension: an update. Curr Opin Nephrol Hypertens 2009; 18:412-420. [PMID: 19654544 PMCID: PMC3722593 DOI: 10.1097/mnh.0b013e32832f5775] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
PURPOSE OF REVIEW Renal proximal tubular sodium reabsorption is regulated by sodium transporters, including the sodium glucose transporter, sodium amino acid transporter, sodium hydrogen exchanger isoform 3 and sodium phosphate cotransporter type 2 located at the luminal/apical membrane, and sodium bicarbonate cotransporter and Na+/K+ATPase located at the basolateral membrane. This review summarizes recent studies on sodium transporters that play a major role in the increase in blood pressure in essential/polygenic hypertension. RECENT FINDINGS Sodium transporters and Na+/K+ATPase are segregated in membrane lipid and nonlipid raft microdomains that regulate their activities and trafficking via cytoskeletal proteins. The increase in renal proximal tubule ion transport in polygenic hypertension is primarily due to increased activity of NHE3 and Cl/HCO3 exchanger at the luminal/apical membrane and a primary or secondary increase in Na+/K+ATPase activity. SUMMARY The increase in renal proximal tubule ion transport in hypertension is due to increased actions by prohypertensive factors that are unopposed by antihypertensive factors.
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Affiliation(s)
- Xiaoyan Wang
- Center for Molecular Physiology Research, Children's Research Institute, Children's National Medical Center, Washington, District of Columbia, USA
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Chadwick M, Vercoe P, Williams I, Revell D. Dietary exposure of pregnant ewes to salt dictates how their offspring respond to salt. Physiol Behav 2009; 97:437-45. [DOI: 10.1016/j.physbeh.2009.03.017] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2008] [Revised: 03/17/2009] [Accepted: 03/17/2009] [Indexed: 11/29/2022]
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Harshfield GA, Dong Y, Kapuku GK, Zhu H, Hanevold CD. Stress-induced sodium retention and hypertension: a review and hypothesis. Curr Hypertens Rep 2009; 11:29-34. [PMID: 19146798 DOI: 10.1007/s11906-009-0007-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Hypertension--an important health problem in industrialized nations--is particularly significant in blacks and obese individuals, in whom it is hypothesized to result from impaired renal sodium regulation. We reviewed studies that identified individuals with impaired sodium regulation by examining the natriuretic response to mental stress. A significant percentage of black and obese individuals retain or have a diminished natriuretic response to mental stress despite increased blood pressure (BP). This contributes a volume component to the normal resistance-mediated BP increase, and BP remains elevated after the stressor ceases until the volume expansion diminishes. The stress exposes these individuals to greater cardiovascular load. This response pattern has been linked to renin-angiotensin-aldosterone system activity, and is associated with premature target-organ damage. Assessing stress-induced sodium retention provides a method to identify patients with impaired sodium regulation without using a dietary protocol that poses adherence difficulties, or complicated laboratory assessments. Furthermore, research using this technique indicates the effectiveness of renin-angiotensin-aldosterone system blockers in correcting impaired sodium regulation and consequent hypertension in these individuals.
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Abstract
Pharmacological and physiological phenomena suggest that cells somewhere inside the central nervous system are responsive to aldosterone. Here, we present the fundamental physiological limitations for aldosterone action in the brain, including its limited blood-brain barrier penetration and its substantial competition from glucocorticoids. Recently, a small group of neurons with unusual sensitivity to circulating aldosterone were identified in the nucleus of the solitary tract. We review the discovery and characterization of these neurons, which express the enzyme 11beta-hydroxysteroid dehydrogenase type 2, and consider alternative proposals regarding sites and mechanisms for mineralocorticoid action within the brain.
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Affiliation(s)
- Joel C Geerling
- Dept. of Anatomy and Neurobiology-Box 8108, Washington Univ. School of Medicine, 660 S. Euclid Ave., St. Louis, MO 63110, USA.
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Bagrov AY, Shapiro JI, Fedorova OV. Endogenous cardiotonic steroids: physiology, pharmacology, and novel therapeutic targets. Pharmacol Rev 2009; 61:9-38. [PMID: 19325075 PMCID: PMC2763610 DOI: 10.1124/pr.108.000711] [Citation(s) in RCA: 384] [Impact Index Per Article: 25.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Endogenous cardiotonic steroids (CTS), also called digitalis-like factors, have been postulated to play important roles in health and disease for nearly half a century. Recent discoveries, which include the specific identification of endogenous cardenolide (endogenous ouabain) and bufadienolide (marinobufagenin) CTS in humans along with the delineation of an alternative mechanism by which CTS can signal through the Na(+)/K(+)-ATPase, have increased the interest in this field substantially. Although CTS were first considered important in the regulation of renal sodium transport and arterial pressure, more recent work implicates these hormones in the regulation of cell growth, differentiation, apoptosis, and fibrosis, the modulation of immunity and of carbohydrate metabolism, and the control of various central nervous functions and even behavior. This review focuses on the physiological interactions between CTS and other regulatory systems that may be important in the pathophysiology of essential hypertension, preeclampsia, end-stage renal disease, congestive heart failure, and diabetes mellitus. Based on our increasing understanding of the regulation of CTS as well as the molecular mechanisms of these hormone increases, we also discuss potential therapeutic strategies.
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Affiliation(s)
- Alexei Y Bagrov
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, 5600 Nathan Shock Dr., Baltimore, MD 21224, USA.
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Ritz E, Mehls O. Salt restriction in kidney disease--a missed therapeutic opportunity? Pediatr Nephrol 2009; 24:9-17. [PMID: 18535843 PMCID: PMC2644745 DOI: 10.1007/s00467-008-0856-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2008] [Revised: 04/09/2008] [Accepted: 04/10/2008] [Indexed: 11/24/2022]
Abstract
The importance of salt restriction in the treatment of patients with renal disease has remained highly controversial. In the following we marshal the current evidence that salt plays a definite role in the genesis of hypertension and target organ damage, point to practical problems of salt restriction, and report on novel pathomechanisms of how salt affects blood pressure and causes target organ damage.
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Affiliation(s)
- Eberhard Ritz
- Department of Internal Medicine, Ruperto Carola University of Heidelberg, Nierenzentrum, Im Neuenheimer Feld 162, 69120, Heidelberg, Germany.
| | - Otto Mehls
- Division of Pediatric Nephrology, University Children’s Hospital of Heidelberg, Heidelberg, Germany
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Current World Literature. Curr Opin Nephrol Hypertens 2009; 18:91-3. [DOI: 10.1097/mnh.0b013e32831fd875] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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68
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Gao F, Sui D, Garavito RM, Worden RM, Wang DH. Salt intake augments hypotensive effects of transient receptor potential vanilloid 4: functional significance and implication. Hypertension 2008; 53:228-35. [PMID: 19075100 DOI: 10.1161/hypertensionaha.108.117499] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
To test the hypothesis that activation of the transient receptor potential vanilloid 4 (TRPV4) channel conveys a hypotensive effect that is enhanced during salt load, male Wistar rats fed a normal-sodium (0.5%) or high-sodium (HS; 4%) diet for 3 weeks were given 4 alpha-phorbol 12,13-didecanoate (4 alpha-PDD), a specific TRPV4 activator, in the presence or absence of capsazepine, a selective TRPV1 blocker, ruthenium red, a TRPV4 blocker, or TRPV4 small hairpin RNA that selectively knockdowns TRPV4. 4 alpha-PDD (1, 2.5, or 5 mg/kg IV) dose-dependently decreased mean arterial pressure (P<0.05). HS enhanced 4 alpha-PDD-induced depressor effects as well as 4 alpha-PDD-mediated release of calcitonin gene-related peptide and substance P (P<0.001). Ruthenium red markedly blunted (P<0.001), whereas capsazepine slightly attenuated (P<0.05) 4 alpha-PDD-induced depressor effects in HS and normal-sodium diet rats. Ruthenium red alone increased baseline mean arterial pressure in both HS and normal-sodium diet rats with a greater magnitude in the former (P<0.05). Western blot analysis showed that HS increased TRPV4 expression in dorsal root ganglia and mesenteric arteries (P<0.05) but not the renal cortex and medulla. Gene-silencing approach revealed that TRPV4 small hairpin RNA downregulated TRPV4 expression leading to blunted 4 alpha-PDD-induced hypotension (P<0.05). Thus, TRPV4 activation decreases blood pressure in rats given a normal-sodium diet. HS enhances TRPV4 expression in sensory nerves/mesenteric arteries and TRPV4-mediated depressor effects and calcitonin gene-related peptide/substance P release such that HS causes a greater increase in blood pressure when TRPV4 is blocked. Our data indicate that TRPV4 activation may constitute a compensatory mechanism in preventing salt-induced increases in blood pressure.
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Affiliation(s)
- Feng Gao
- Department of Medicine, Michigan State University, East Lansing, MI 48824, USA
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Koga Y, Hirooka Y, Araki S, Nozoe M, Kishi T, Sunagawa K. High Salt Intake Enhances Blood Pressure Increase during Development of Hypertension via Oxidative Stress in Rostral Ventrolateral Medulla of Spontaneously Hypertensive Rats. Hypertens Res 2008; 31:2075-83. [DOI: 10.1291/hypres.31.2075] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Bagrov AY, Shapiro JI. Endogenous digitalis: pathophysiologic roles and therapeutic applications. NATURE CLINICAL PRACTICE. NEPHROLOGY 2008; 4:378-92. [PMID: 18542120 PMCID: PMC2574729 DOI: 10.1038/ncpneph0848] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2008] [Accepted: 04/29/2008] [Indexed: 12/22/2022]
Abstract
Endogenous digitalis-like factors, also called cardiotonic steroids, have been thought for nearly half a century to have important roles in health and disease. The endogenous cardiotonic steroids ouabain and marinobufagenin have been identified in humans, and an effector mechanism has been delineated by which these hormones signal through the sodium/potassium-transporting ATPase. These findings have increased interest in this field substantially. Although cardiotonic steroids were first considered important in the regulation of renal sodium transport and arterial pressure, subsequent work has implicated these hormones in the control of cell growth, apoptosis and fibrosis, among other processes. This Review focuses on the role of endogenous cardiotonic steroids in the pathophysiology of essential hypertension, congestive heart failure, end-stage renal disease and pre-eclampsia. We also discuss potential therapeutic strategies that have emerged as a result of the increased understanding of the regulation and actions of cardiotonic steroids.
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Affiliation(s)
- Alexei Y Bagrov
- Hypertension Unit at Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, NIH, Baltimore 21224, MD, USA.
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Sakae R, Ishikawa A, Niso T, Komori Y, Aiba T, Kawasaki H, Kurosaki Y. Decreased Lithium Disposition to Cerebrospinal Fluid in Rats with Glycerol-induced Acute Renal Failure. Pharm Res 2008; 25:2243-9. [DOI: 10.1007/s11095-008-9612-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2008] [Accepted: 04/25/2008] [Indexed: 10/21/2022]
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Alzheimer disease research: have we forgotten the cerebrovascular circulation? Alzheimer Dis Assoc Disord 2008; 22:1-3. [PMID: 18317240 DOI: 10.1097/wad.0b013e31815ccd7c] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Koltsova SV, Gusakova SV, Anfinogenova YJ, Baskakov MB, Orlov SN. Vascular Smooth Muscle Contraction Evoked by Cell Volume Modulation: Role of the Cytoskeleton Network. Cell Physiol Biochem 2008; 21:29-36. [DOI: 10.1159/000113744] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/15/2007] [Indexed: 01/23/2023] Open
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