Jun 1, 1976

Cellular basis for increased sensitivity of vascular smooth muscle in spontaneously hypertensive rats

Circulation Research
K Hermsmeyer

Abstract

There is evidence that hypersensitivity of vascular muscle to neurotransmitters contributes to the development of hypertension. Comparison of the caudal arteries of spontaneously hypertensive rats (SHR) and their genetically related Kyoto-Wistar normotensive control rats (KNR) showed that although there is no difference in membrane potential under unstimulated conditions, greater depolarization of the SHR vascular muscle cells by norepinephrine occurs at concentrations which cause greater contraction. The mechanism for the increased depolarization and resulting increase in contraction appears to be a lower intracellular potassium ion activity in SHR vascular muscle cells, which results in a lower contribution of potassium gradient to membrane potential. Experiments to determine the sensitivity of isolated, dispersed chick omphalomesenteric vascular muscle cells to neurotransmitters showed remarkably low thresholds to the neutransmitters norepinephrine, serotonin, and acetylcholine, but not potassium chloride. The high sensitivity of isolated cells to neurotransmitters suggests that factors in the intact vessel may cause thresholds to be high, possibly implying that alterations in a neurotrophic mechanism might be responsible fo...Continue Reading

Mentioned in this Paper

Muscle, Smooth, Vascular
Rats, Inbred SHR
Arterial System
Serotonin Measurement
Neurosteroids
Muscle Cells
Protoplasm
Resting Potentials
Blood Vessel
Serotonin

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