Features of ionic transport processes in a model of arterial hypertension

Aim.To study the ionic mechanisms which underlie regulation contractile activity of vascular smooth muscles and the erythrocytes membrane potential from spontaneously hypertensive rats.Materials and methods.The effect of acetylcholine (ACX), 10 μM, and Ca2+ -ionophore A23187, 10 μM, on the contractile reactions of isolated smooth muscle segments of the aorta from 11-week-old spontaneously hypertensive rats (SHR) and Wistar – Kyoto rats (WKY) induced by phenylephrine (PE), 1 μM, was measured by the mechanography. 11-week-old SHR were divided into control and experimental groups depending on the drug administration (amlodipine 10 mg/kg given intragastrically). Blood pressure (BP) in SHR was measured before and after treatment. The amplitude of the hyperpolarizating response (HO) and the activity of Ca2+-dependent K+-channels of the erythrocyte membrane of SHR were performed with potentiometric method.Results.In response to the stimulating effect of the ACX or the calcium ionophore A23187, the smooth muscle segments of the aorta from the WKY and SHR precontracted with PE were relaxed. To the addition of the ACX, the vascular segments of the SHR responded with a stronger dilatation than the WKY segments, but not the action of the Ca2+-ionophore. Treatment of SHR with blocker of Ca2+-channels of L-type amlodipine caused a decrease the BP, and an increase in the relaxing effect of intact aortic segments on the ACX and Ca2+-ionophore. There was an increase the amplitude of HO and activity of Ca2+-dependent K+-channels of the erythrocyte membrane from SHR.Conclusion.Relaxation of vascular smooth muscle in SHR is caused by changes in the endothelial function and Ca2+-dependent ionic conductivity of the myocyte membrane. An increase of the hyperpolarizating response of the erythrocyte membrane from rats with spontaneous hypertension is associated with activation of potassium channels. The selective effect on these intracellular targets can serve as a basis for the development of antihypertensive drugs.

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Calcium Accumulation and Calcium Binding by the Cell Membranes of Cardiomyocytes and Smooth Muscle of Aorta in Spontaneously Hypertensive Rats

Clinical Science ◽

10.1042/cs059207s ◽

1980 ◽

Vol 59 (s6) ◽

pp. 207s-209s ◽

Cited By ~ 23

Author(s):

S. N. Orlov ◽

Yu. V. Postnov

Keyword(s):

Smooth Muscle ◽

Erythrocyte Membrane ◽

Calcium Binding ◽

Spontaneously Hypertensive Rats ◽

Plasma Membranes ◽

Hypertensive Rats ◽

Binding Ability ◽

Spontaneously Hypertensive ◽

Aortic Smooth Muscle ◽

Lower Ability

1. The ability of isolated membrane fractions of cardiomyocytes, aortic smooth muscle and erythrocytes from spontaneously hypertensive rats to bind calcium was investigated isotopically. 2. Plasma membranes of aortic smooth muscle and erythrocytes of spontaneously hypertensive rats possess a lower calcium-binding ability than preparations from normotensive controls. 3. Sarcoplasmic reticulum from the myocardium of spontaneously hypertensive rats had a lower ability to accumulate calcium. 4. Changes in the calcium-binding ability of the erythrocyte membrane of spontaneously hypertensive rats was related to the diminution of the amount of exchangeable calcium on the inner part of the membrane. The latter may be the cause of the increase of erythrocyte membrane permeability for sodium in spontaneously hypertensive rats and in patients with essential hypertension.

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