Decrease of calcium binding by the red blood cell membrane in spontaneously hypertensive rats and in essential hypertension

Ca binding in the red blood cell (RBC) membrane of spontaneously hypertensive rats (SHR) and of patients with essential hypertension was studied. Under conditions of physiological concentration of free Ca in the incubation medium of RBC the outer part of the membrane binds 393±32 and 435±30 nmole of Ca per ml of RBC in rats and humans, respectively, without essential differences in the amount of Ca in hypertensive individuals as compared to the normotensive controls.The membrane of red blood cell ghosts (RBCgh) at concentrations of free Ca corresponding to its intracellular concentration binds 4.28±0.39 and 3.53±0.15 nmole of Ca per mg of protein of RBCgh in rats and humans, respectively. This part of membrane-bound Ca pool (most probably related to the inner part of the red blood cell membrane) is reduced by 48% in SHR and by 28% in patients with essential hypertension as compared to normotensive controls.It is suggested that the decrease of Ca binding ability of the RBC membrane in both types of hypertension studied may be a pattern of a more widespread cell membrane defect.     

Alteration of the intracellular calcium pool of adipose tissue in spontaneously hypertensive rats

The intracellular calcium pool of adipose tissue was estimated by studying the kinetics of⁴⁵Ca efflux from the tissue of 9-week old spontaneously hypertensive (SHR) and normotensive Kyoto-Wistar (NKWR) rats subjected to peripheral immunosympathectomy (nerve growth factor antiserum treatment of newborn rats) and in intact (shamtreated) animals of both strains. The development of hypertension in SHR was prevented by immunosympathectomy, however, both groups, SHR-intact and immunosympathectomized rats showed an increase in the intracellular calcium content of adipocytes. These results indicate that the alteration of the membrane control over intracellular calcium distribution in adipose tissue of SHR cannot be attributed to an enhanced activity of the sympathetic nervous system.     

Altered permeability of the erythrocyte membrane for sodium and potassium ions in spontaneously hypertensive rats

Summary Permeability of the erythrocyte membrane for sodium and potassium ions was studied in 8–10-week old spontaneously hypertensive rats (SHR, Kyoto Wistar strain), normotensive Wistar and Sprague-Dawley rats.The rate constant of Na/Na exchange was considerably greater in the SHR than in the normotensive Wistar and Sprague-Dawley rats. This difference remained the same in the rats adrenalectomized 7 days prior to the experiment. The maximum difference in the constants was found when the sodium pump was blocked by ouabain.The accumulation of⁴²K in the erythrocytes of the SHR (the sodium pump being blocked) took place at a considerably slower rate, and the K⁺ washout into a potassium-free medium was faster than in the normotensive Wistar and Sprague-Dawley rats.These results seem to indicate a higher permeability of the SHR's erythrocyte membrane for Na⁺ and K⁺ions, as compared to normotensive Wistar and Sprague-Dawley strains. It is suggested that the increased permeability of the erythrocyte membrane for Na⁺ and K⁺ in the SHR may reflect a more widespread cell membrane defect, which could serve as a general cause for activating the mechanisms maintaining high blood pressure.     

Glucose uptake and triglyceride synthesis in adipose tissue of spontaneously and renal hypertensive rats (Alterations revealed by adrenalectomy)

Rats with renal and spontaneous hypertension do not differ from control normotensive rats in¹⁴C-glucose uptake and triglyceride synthesis by the adipose tissue in vitro, both with and without insulin stimulation. Adrenalectomy (which eliminates the stabilizing effect of the corticosteroid hormones on the adipocyte membrane) reveals the differences between the hypertensive and normotensive rats in the response of the adipose tissue to insulin. While the adrenalectomized control rats show a significantly lowered sensitivity of the adipocytes to insulin, the adrenalcetomized hypertensive rats do not reveal a noticeable change in glucose uptake and triglyceride synthesis under insulin stimulation of glucose transport (the adipose tissue of hypertensive rats doesn't notice adrenalectomy).The data obtained may indicate changes in the properties of the adipocyte membranes of rats with chronic arterial hypertension and suggest the presence of an extensive alteration of the function of cell membranes in both types of hypertension.     

Reduction of the β-cell component of pancreatic islets in spontaneously hypertensive rats

Summary A morphometric study of the pancreatic islets in young spontaneously hypertensive rats (SHR, Okamoto and Aoki Wistar strain) and in normotensive Wistar rats (NWR) of the same age revealed that the SHR (in prehypertensive and in early hypertensive stages) had a significantly smaller mass of islet tissue and that the number of islets in the SHR was reduced by half. The ratio between the total masses of the pancreatic islets for the NWR and the SHR at the prehypertensive and early hypertensive stages was found to be: 10.530.61, respectively. The mass of the islet tissue in the SHR was reduced at the expense of the -cell component of the islets. No morphologic differences were found in the acinous tissue, and the pancreas and body weights were the same in both experimental groups.The glucose tolerance test revealed reduced glucose utilization in the SHR, which may be due to a relative insufficiency of the insulin secretion by the islets upon rapid (i.v.) glucose lodaing. Reduced plasma insulin response to i.v. glucose loading and a reduced rate of insulin utilization were found in the SHR as compared with the NWR.The poor development of the -cell tissue may be attributed either to the specific effect of the enhanced catecholamine excretion or to a low insulin requirement of the cell tissue membranes (insulin targets) as a consequence of the membrane ion transport alteration in spontaneous hypertension.Dr. Yuvenaly V. Postnov, M.D., D.Sc., Head of the Department of PathomorphologyDr. Svetlana I. Gorkova, M.D., Cand.Sc., pathologistDr. Larisa P. Solovyova M.D. boichemistThe authors are grateful to Mrs. L. A. Petrunina, Mrs. I. A. Zohichareva, Miss G. A. Orlova, Mrs. W. I. Tsarkova, and Miss A. V. Shapilova for valuable technical assistance.     

Increased sensitivity of adipose tissue of spontaneously hypertensive rats to ACTH

The action of ACTH on lipolysis was studied in the adipose tissue of rats with spontaneous and renal hypertension and also in normotensive rats of corresponding control groups. The sensitivity of the adipose tissue of SHR rats to ACTH was shown to be higher than in the normotensive control. Evidence was obtained that this increase in sensitivity is due to the state or quantity of intracellular calcium. In rats with renal hypertension no such increase in sensitivity of their adipose tissue to ACTH was found.Department of Pathomorphology, No. 4, Board, Ministry of Health of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR E. I. Chazov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 88, No. 7, pp. 23–26, July, 1979.     

Biosynthesis of renal prostaglandins in spontaneously hypertensive rats

The biosynthesis of prostaglandins (PG) E₂ and F₂ from [¹⁴C]arachidonic acid by renal medullary tissue of rats with spontaneous hypertension and of normotensive Wistar rats was investigated at different ages (1.5 and 3.5 months). In animals with spontaneous hypertension the synthesis of PG E₂ from arachidonic acid was at a much lower level than in Wistar rats. The biosynthesis of PG F₂ in these animals was virtually indistinguishable from normal. No age differences were found in PG formation by the kidneys of rats with spontaneous hypertension, whereas in Wistar rats PG E₂ biosynthesis was depressed at the age of 3.5 months.Laboratory of Pathophysiology, Institute of Pediatrics, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of medical Sciences of the USSR A. M. Chernukh.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 83, No. 6, pp. 659–661, June, 1977     

Changes in brainstem and spinal adrenoceptor binding with ageing in spontaneously hypertensive and Wistar-Kyoto rats

Adrenoceptor binding in membranes prepared from the brainstem and thoracic spinal cord of male spontaneously hypertensive (SHR) and Wistar-Kyoto (WKY) rats aged 6 and 36-40 weeks has been compared. Binding of [3H]prazosin (alpha 1-receptors), [3H]rauwolscine (alpha 2-receptors) and [3H]dihydroalprenolol (DHA: beta-receptors) fell with age in both regions in both strains. Strain, independent of age, was also a significant determinant of binding for all three ligands in brainstem and for [3H]DHA in spinal cord. The changes in receptor binding may reflect differences in noradrenergic activity with age and between SHR and WKY rats.     

自发性高血压大鼠的基因组多态性

目的:应用随机扩增多态DNA聚合酶链反应（RAPD-PCR）技术分析自发性高血压大鼠（SHR）的基因组多态性。 方法:运用100条引物对WKY和SHR的DNA进行RAPD-PCR扩增，琼脂糖凝胶电泳观察。 结果:与WKY相比，100条引物中有13条引物出现基因组多态性，SHR扩增产物的电泳条带出现增加、丢失、移位和密度改变，其它87条引物扩增结果无明显改变。 结论:SHR存在基因组多态性，RAPD-PCR方法可用于检测SHR的基因组多态性。     

自发性高血压大鼠主动脉结构重建

本文采用组织形态学方法和计算机图象分析,研究了４－５５周自发性高血压大鼠胸主动脉几何形态及显微结构成分的重建。结果显示：随着血压增高和年龄增长,ＳＨＲ主主显微结构成分的重均比ＷＫＹ大鼠显著,说明压力因素对血管重建起重要作用。ＳＨＲ主 动脉肥厚为研。高血压早期以血管平滑肌细胞肥大和ＶＳＭＣ面积增加为主,高血压老龄期则以胶原纤维积聚为特征。ＶＳＭＣ及细胞外基质的变化构成了ＳＨＲ主动脉重建的重要过程。     

Effects of rapid and slow cooling on thermoregulatory reactions in hypertensive rats after administration of calcium

Iontophoretic administration of calcium ions into the skin close to the application site of a cold stimulus decreased the threshold of thermoregulatory reactions in hypertensive rats to a greater extent than in normotensive control animals, which may be evidence that the tissues involved in thermoregulatory reactions to cold have a greater sensitivity to calcium in hypertensive rats. The initially earlier onset of vascular and metabolic reactions and the increase in the vascular reaction seen in hypertensive rats became more marked after administration of calcium. Treatment with calcium, increasing the vascular reaction to cooling, facilitates a more marked discrimination between hyper-and normotensive animals in terms of the appearance of the vasoconstrictor reactions of skin blood vessels in response to cold. The effects of the added calcium on cold-dependent reactions depended on the rate of cooling. __________ Translated from Rossiiskii Fiziologicheskii Zhurnal imeni I. M. Sechenova, Vol. 91, No. 8, pp. 970–979, August, 2005.     

VEGF在自发性高血压大鼠肾小球内的表达

目的研究血管内皮生长因子（VEGF）在幼年及成年自发性高血压大鼠（SHR）肾小球内的表达,探讨它在高血压病肾损害中的作用。方法6周龄SHR和WKY大鼠各10只,15月龄SHR和WKY大鼠各20只,将肾组织进行常规病理和免疫组化染色（SP法）,利用计算机图像分析定量肾组织内的微血管数和VEGF的表达。结果VEGF蛋白主要分布于肾小球内的足细胞和球内系膜细胞,15月龄SHR组的阳性反应程度显著高于其余3组（P〈0．05）,而其他各组间无显著差异。结论推测VEGF可能参与高血压肾损害的发病过程。     

Acquisition of conditioned suppression and responsivity to thermal stimulation in spontaneously hypertensive,renal hypertensive and normotensive rats

The acquisition of conditioned suppression of instrumental responding and responsivity to thermal stimulation were assessed in spontaneously hypertensive rats of the Okamoto-Aoki strain (SHRs), renal hypertensive rats of the Wistar-Kyoto strain (WKYs), and normotensive WKY rats. Spontaneously hypertensive rats showed significantly faster acquisition of conditioned suppression than age-matched WKY normotensive rats. This acquisition difference between SHRs and normotensive WKYs was maintained even following chronic preexposure to shock alone; a treatment that retarded normal acquisition of conditioned suppression. In contrast, renal hypertensive WKYs acquired conditioned suppression at the same rate as age-matched normotensive WKYs. Spontaneously hypertensive rats and renal hypertensive WKYs both showed significantly longer latencies than normotensive WKYs to respond to thermal stimulation using a hot-plate assay. These outcomes suggest that the relationship between blood pressure and the acquisition of conditioned suppression in SHRs is either pleiotrophic or a consequence of random fixation, and that acquisition of conditioned suppression may serve as a valuable marker variable of hypertension in the SHR. The dissociation between acquisition of conditioned suppression and responsivity to thermal stimulation suggests that different mechanisms may mediate nociceptive responses to shock and thermal stimulation in these models of hypertension.