Most cited article - PubMed ID 22827876
Age-dependent salt hypertension in Dahl rats: fifty years of research
This is a protocol for a Cochrane Review (intervention). The objectives are as follows: To evaluate the effect on blood pressure - measured as changes in systolic and diastolic blood pressure (mmHg) using standardised measurement methods - of substituting sodium salt with other edible salts (e.g. potassium chloride, magnesium chloride) in people with diabetes mellitus.
- MeSH
- Potassium Chloride administration & dosage MeSH
- Magnesium Chloride administration & dosage MeSH
- Diabetes Mellitus * MeSH
- Adult MeSH
- Hypertension * diet therapy MeSH
- Blood Pressure * drug effects MeSH
- Sodium Chloride, Dietary * administration & dosage MeSH
- Humans MeSH
- Randomized Controlled Trials as Topic MeSH
- Check Tag
- Adult MeSH
- Humans MeSH
- Publication type
- Journal Article MeSH
- Names of Substances
- Potassium Chloride MeSH
- Magnesium Chloride MeSH
- Sodium Chloride, Dietary * MeSH
Sympathetic hyperactivity and relative NO deficiency are characteristic alterations in both genetic and salt hypertension. The contribution of these abnormalities to blood pressure (BP) maintenance can be determined in conscious rats using a consecutive blockade of particular vasoactive systems. Thus, the contribution of pressor effects of angiotensin II to the maintenance of high BP is usually small, but the role of renin-angiotensin system in the development of hypertension mediated by central and peripheral effects of angiotensin II on sympathetic activity is highly important. This is even true in angiotensin-dependent hypertension of heterozygous Ren-2 transgenic rats in which sympathetic hyperactivity is increasing with age. Central sympathoexcitation in this hypertensive model can be inhibited by lower losartan doses than peripheral angiotensin II-dependent vasoconstriction. This experimental model also yielded important knowledge on nephroprotective effects of new therapeutic drugs - endothelin receptor type A blockers. A considerable part of sympathetic vasoconstriction is dependent on the interaction of Ca2+ sensitization (RhoA/Rho kinase pathway) and Ca2+ influx (through L-VDCC). The blockade of these pathways prevents a major part of sympathetic vasoconstriction. Ca2+ sensitization seems to be attenuated in genetic hypertension in order to compensate increased Ca2+ influx. In contrast, enhanced Ca2+ sensitization is a hallmark of salt sensitivity in Dahl rats in which salt hypertension is dependent on increased Ca2+ influx. The attention should also be paid to the impairment of arterial baroreflex sensitivity which permits enhanced BP responses to pressor or depressor stimuli. Some abnormalities can be studied in blood vessels isolated from hypertensive rats but neither conduit arteries nor mesenteric resistance arteries represent the vascular beds decisive for the increased peripheral resistance and high BP. Keywords: Sympathetic vasoconstriction, NO-dependent vasodilatation, Calcium sensitization, Calcium influx, Arterial baroreflex, Spontaneously hypertensive rats, Salt hypertensive Dahl rats, Ren-2 transgenic rats, RAS blockade, SNS blockade, NOS inhibition, Endothelin, Vascular contraction and relaxation, Isolated conduit and resistance arteries, EDCF, PGI2, BKCa channels.
- MeSH
- Hypertension * physiopathology metabolism MeSH
- Blood Pressure physiology MeSH
- Humans MeSH
- Disease Models, Animal MeSH
- Renin-Angiotensin System physiology MeSH
- Sympathetic Nervous System * physiopathology metabolism MeSH
- Vasodilation * physiology drug effects MeSH
- Vasoconstriction * physiology drug effects MeSH
- Animals MeSH
- Check Tag
- Humans MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Review MeSH
Hypertension is the most prevalent cardiovascular disease of the adult population and is closely associated with serious cardiovascular events. The burden of hypertension with respect to vascular and other organ damage is greater in women. These sex differences are not fully understood. The unique feature in women is their transition to menopause accompanied by profound hormonal changes that affect the vasculature that are also associated with changes of blood pressure. Results from studies of hormone replacement therapy and its effects on the cardiovascular system are controversial, and the timing of treatment after menopause seems to be important. Therefore, revealing potential sex- and sex hormone-dependent pathophysiological mechanisms of hypertension in experimental studies could provide valuable information for better treatment of hypertension and vascular impairment, especially in postmenopausal women. The experimental rat models subjected to ovariectomy mimicking menopause could be useful tools for studying the mechanisms of blood pressure regulation after menopause and during subsequent therapy.
- MeSH
- Hormone Replacement Therapy MeSH
- Hypertension * MeSH
- Cardiovascular Diseases * epidemiology MeSH
- Blood Pressure physiology MeSH
- Rats MeSH
- Menopause physiology MeSH
- Animals MeSH
- Check Tag
- Rats MeSH
- Male MeSH
- Female MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Review MeSH
Salt hypertensive Dahl rats are characterized by sympathoexcitation and relative NO deficiency. We tested the hypothesis that the increased blood pressure (BP) response to fasudil in salt hypertensive Dahl rats is due to augmented calcium sensitization in the salt-sensitive strain and/or due to their decreased baroreflex efficiency. BP reduction after acute administration of nifedipine (an L-type voltage-dependent calcium channel blocker) or fasudil (a Rho kinase inhibitor) was studied in conscious intact rats and in rats subjected to acute NO synthase inhibition or combined blockade of the renin-angiotensin system (captopril), sympathetic nervous system (pentolinium), and NO synthase (L-NAME). Intact salt-sensitive (SS) Dahl rats fed a low-salt diet had greater BP responses to nifedipine (-31 ± 6 mmHg) or fasudil (-34 ± 7 mmHg) than salt-resistant (SR) Dahl rats (-16 ± 4 and -17 ± 2 mmHg, respectively), and a high-salt intake augmented the BP response only in SS rats. These BP responses were doubled after acute NO synthase inhibition, indicating that endogenous NO attenuates both calcium entry and calcium sensitization. Additional pentolinium administration, which minimized sympathetic compensation for the drug-induced BP reduction, magnified the BP responses to nifedipine or fasudil in all groups except for salt hypertensive SS rats due to their lower baroreflex efficiency. The BP response to the calcium channel blocker nifedipine can distinguish SS and SR rats even after calcium sensitization inhibition by fasudil, which was not seen when fasudil was administered to nifedipine-pretreated rats. Thus, enhanced calcium entry (potentiated by sympathoexcitation) in salt hypertensive Dahl rats is the abnormality that is essential for their BP increase, which was further augmented by increased calcium sensitization in salt-sensitive Dahl rats.
- Keywords
- Baroreflex efficiency, Fasudil, Nifedipine, Nitric oxide, Rho kinase, Sympathetic tone, Voltage-dependent calcium channels,
- MeSH
- Hypertension * drug therapy MeSH
- Blood Pressure MeSH
- Rats MeSH
- Sodium Chloride, Dietary * MeSH
- Rats, Inbred Dahl MeSH
- Calcium MeSH
- Vasoconstriction MeSH
- Animals MeSH
- Check Tag
- Rats MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Names of Substances
- Sodium Chloride, Dietary * MeSH
- Calcium MeSH
The important participation of sympathetic nervous system in various forms of experimental hypertension is well known. This is also true for salt hypertension elicited by excess salt intake in Dahl salt-sensitive rats (for review see Zicha et al. 2012). Two recent studies in Dahl rats (Zicha et al. 2019, Puleo et al. 2020) evaluated the hypothesis on the role of beta-adrenergic WNK4-NCC pathway in salt-sensitive hypertension which has been proposed by Mu et al. (2011). Although these studies differed in many experimental details, both of them demonstrated a major importance of alpha1- rather than beta-adrenergic mechanisms for the development of salt hypertension in this rat strain.
- MeSH
- Sodium Chloride MeSH
- Hypertension * MeSH
- Rats MeSH
- Sodium Chloride, Dietary * MeSH
- Rats, Inbred Dahl MeSH
- Sympathetic Nervous System MeSH
- Animals MeSH
- Check Tag
- Rats MeSH
- Animals MeSH
- Publication type
- Comment MeSH
- Editorial MeSH
- Names of Substances
- Sodium Chloride MeSH
- Sodium Chloride, Dietary * MeSH
Sex-related differences were observed not only in human but also in experimental hypertension. The aim of our study was to compare blood pressure (BP) of aged male and female heterozygous transgenic rats (TGR) harboring Ren-2 mouse gene, with their normotensive Hannover Sprague-Dawley (HanSD) controls. At the age of 9 months, systolic (SBP) and diastolic blood pressure (DBP) were measured by a direct puncture of carotid artery in rats awaking from isoflurane anesthesia. Thiobarbituric acid-reactive species (TBARS) formation was monitored as indicator of lipid peroxidation damage in heart, kidney and liver, whereas intracellular content of reduced glutathione was determined in the same organs as the main intracellular antioxidant. Furthermore, plasma triglycerides and total cholesterol as well as high-density lipoprotein (HDL) and low-density lipoprotein (LDL) fractions of cholesterol were measured. As compared to HanSD rats, we found significantly elevated BP only in male TGR (MAP: 123±1 vs. 171±5, SBP: 150±2 vs. 208±7, and DBP: 99±3 vs. 140±4 mm Hg), but not between TGR and HanSD females, which were both normotensive. We also did not find any significant differences in TBARS and reduced glutathione in the three above mentioned organs as well as in plasma cholesterol or its HDL and LDL fractions between transgene-negative HanSD and TGR animals of either sex. However, we found significant sex differences in TBARS, glutathione and plasma lipids in both rat strains. Our results confirmed that aged TGR exhibit a marked sexual BP dimorphism, which does not seem to be dependent on oxidative stress or abnormal cholesterol metabolism.
- MeSH
- Blood Pressure physiology MeSH
- Rats MeSH
- Mice MeSH
- Oxidative Stress physiology MeSH
- Sex Characteristics * MeSH
- Rats, Sprague-Dawley MeSH
- Rats, Transgenic MeSH
- Renin genetics metabolism MeSH
- Aging genetics metabolism MeSH
- Animals MeSH
- Check Tag
- Rats MeSH
- Male MeSH
- Mice MeSH
- Female MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Names of Substances
- Ren2 protein, mouse MeSH Browser
- Renin MeSH