For decades, essential hypertension has been primarily viewed from a hemodynamic, neural, and renal perspective. However, based on mounting evidence from clinical, epidemiological, and experimental studies, it has become increasingly recognized that disturbances in carbohydrate and lipid metabolism often accompany high blood pressure, and that essential hypertension may also represent a disorder of cardiovascular endocrinology and metabolism (1, 2). In patients with essential hypertension, clustering of metabolic cardiovascular risk factors -including glucose intolerance, hyperinsulinemia, and hypertriglyceridemiamay promote susceptibility to target organ damage and partly explain why conventional antihypertensive agents have failed to reduce the risk for coronary heart disease to the extent predicted from epidemiological studies (2).Recently, a provocative hypothesis has emerged in which inherited disorders of carbohydrate or lipid metabolism are held to be at the core of the hypertension syndrome and to contribute to the primary pathogenesis of increased blood pressure. Studies in nonobese subjects with a family history of hypertension and in a variety of experimental animal models have suggested that alterations in carbohydrate and/or lipid metabolism can influence the regulation of blood pressure and might precede the development of hypertension (3-5). The lack of insulin resistance in patients with secondary forms of hypertension, together with observations of disordered carbohydrate and lipid metabolism in cultured adipocytes from hypertensive animals, indicates that at least some endocrine-metabolic disturbances are not simply a consequence of increased blood pressure (4,(6)(7)(8). Hence, there is intense interest in identifying genetic mechanisms that may underlie the association between increased blood pressure and other cardiovascular risk factors in essential hypertension.The spontaneously hypertensive rat (SHR) is the most Disorders of carbohydrate and lipid metabolism have been reported to cluster in patients with essential hypertension and in spontaneously hypertensive rats (SHRs). A deletion in the Cd36 gene on chromosome 4 has recently been implicated in defective carbohydrate and lipid metabolism in isolated adipocytes from SHRs. However, the role of Cd36 and chromosome 4 in the control of blood pressure and systemic cardiovascular risk factors in SHRs is unknown. In the SHR.BN-Il6/Npy congenic strain, we have found that transfer of a segment of chromosome 4 (including Cd36) from the Brown Norway (BN) rat onto the SHR background induces reductions in blood pressure and ameliorates dietary-induced glucose intolerance, hyperinsulinemia, and hypertriglyceridemia. These results demonstrate that a single chromosome region can influence a broad spectrum of cardiovascular risk factors involved in the hypertension metabolic syndrome. However, analysis of Cd36 genotypes in the SHR and stroke-prone SHR strains indicates that the deletion variant of Cd36 was not critical to the initial selection for hypert...

No abstract

Abnormalities in carbohydrate and lipid metabolism are common in patients with essential hypertension and in the spontaneously hypertensive rat (SHR). To identify chromosome regions contributing to this clustering of cardiovascular risk factors in the SHR, we searched for quantitative trait loci (QTL) associated with insulin resistance, glucose intolerance, and dyslipidemia by using the HXB/BXH recombinant inbred (RI) strains. Analysis of variance in RI strains suggested significant effects of genetic factors. A genome screening of the RI strains with more than 700 markers revealed QTL significantly associated with insulin resistance on Chromosomes (Chrs) 3 and 19. The Chr 19 QTL was confirmed by testing a previously derived SHR-19 congenic strain: transfer of a Chr 19 segment delineated by markers D19Rat57 and D19Mit7 from the Brown Norway (BN/Cr) strain onto the genetic background of the SHR/Ola was associated with decreased insulin and glucose concentrations and ameliorated insulin resistance at the tissue level. These findings suggest that closely linked genes on Chr 19, or perhaps even a single gene with pleiotropic effects, influence the clustering of metabolic disturbances in the SHR-BN model.

No abstract

The aim of the study was to examine whether the circulating cell adhesion molecules, von Willebrand factor (vWf) and endothelin-1, are elevated in patients with essential hypertension with no other risk factors for atherosclerosis and thus may serve as a markers of endothelial dysfunction in uncomplicated hypertension. Furthermore, the effect of treatment with the ACE inhibitor, quinapril, on levels of endothelial dysfunction markers were studied. The levels of adhesion molecules (intercellular cell adhesion molecule-1 [ICAM-1], E-selectin, P-selectin), von Wilebrand factor (vWf) and endothelin-1 were measured in patients with hypertension without any other risk factors of atherosclerosis before and after treatment with quinapril (n = 22) and in normotensive controls (n = 22). Compared with normotensive subjects, the hypertensive patients had significantly higher levels of ICAM-1 (238 vs 208 ng/ml, P = 0.02), vWf (119 vs 105 IU/dl, P Ͻ 0.05) and endothelin-1 (5.76 vs 5.14 fmol/ml, P Ͻ 0.05). Three-month treatment of hyper-

The purpose of this study was to determine whether or not repeated short-term cold water immersions can induce a change in the activity of the sympathetic nervous system and, consequently, in cardiovascular functions in healthy young athletes. Changes in some plasma hormone concentrations were also followed. A single cold water immersion (head-out, at 14 degrees C, for 1 h) increased sympathetic nervous system activity, as evidenced by a four-fold increase (P < 0.05) in plasma noradrenaline concentration. Plasma adrenaline and dopamine concentrations were not increased significantly. Plasma renin-angiotensin activity was reduced by half (P < 0.05) during immersion but plasma aldosterone concentration was unchanged. Stimulation of the sympathetic nervous system during immersion did not induce significant changes in heart rate, but induced peripheral vasoconstriction (as judged from a decrease in skin temperature) and a small increase (by 10%) in systolic and diastolic blood pressures. No clear change in reactivity of the sympathetic nervous system was observed due to repeated cold water immersions (three times a week, for 6 weeks). Neither the plasma renin-angiotensin activity, aldosterone concentration nor cardiovascular parameters were significantly influenced by repeated cold water immersions. A lowered diastolic pressure and an increase in peripheral vasoconstriction were observed after cold acclimation, however. Evidently, the repeated cold stimuli were not sufficient to induce significant adaptational changes in sympathetic activity and hormone production.

No abstract

Abstract-Previous studies with chromosome-Y consomic strains of spontaneously hypertensive rats (SHR) andWistar-Kyoto rats suggest that a quantitative trait locus for blood pressure regulation exists on chromosome Y. To test this hypothesis in the SHR-Brown Norway (BN) model and to study the effects of chromosome Y on lipid and carbohydrate metabolism, we produced a new consomic strain of SHR carrying the Y chromosome transferred from the BN rat. We found that replacing the SHR Y chromosome with the BN Y chromosome resulted in significant decreases in systolic and diastolic blood pressures in the SHR.BN-Y consomic strain (PϽ0.05). To elicit possible dietary-induced variation in lipid and glucose metabolism between the SHR progenitor and chromosome-Y consomic strains, we fed rats a high-fructose diet for 15 days in addition to the normal diet. On the high-fructose diet, the SHR.BN-Y consomic rats exhibited significantly increased levels of serum triglycerides and decreased levels of serum HDL cholesterol versus the SHR progenitor rats. Glucose tolerance and insulin/glucose ratios, however, were similar in both strains on both normal and high-fructose diets. These findings provide direct evidence that a gene or genes on chromosome Y contribute to the pathogenesis of spontaneous hypertension in the SHR-BN model. These results also indicate that transfer of the Y chromosome from the BN rat onto the SHR background exacerbates dietary-induced dyslipidemia in SHR. Thus, genetic variation in genes on the Y chromosome may contribute to variation in blood pressure and lipid levels and may influence the risk for cardiovascular disease.