Interaction of hydralazine with tension development and mechanisms of calcium accumulation in K+-stimulated rabbit aortic strips

A. J. McLean; P. Du Souich; K. W. Barron; A. H. Briggs

Interaction of hydralazine with tension development and mechanisms of calcium accumulation in K⁺-stimulated rabbit aortic strips

A. J. McLean, P. Du Souich, K. W. Barron, A. H. Briggs

Research output: Contribution to journal › Article › peer-review

Abstract

A study was made of the effects of hydralazine on K⁺ contractures in rabbit aortic strips. Measurements were made of effects on tension generation, Ca⁺⁺ accumulation measured using ⁴⁵Ca⁺⁺ (lanthanum method) and ⁴⁵Ca⁺⁺ efflux. Hydralazine relaxed established K⁺ contractures and inhibited tension development when tissue exposure to hydralazine preceded K⁺ depolarization. Both the threshold and the maximum tension responses of strips to Ca⁺⁺ (K⁺-depolarized tissues) were altered by hydralazine in a dose-dependent manner. The Ca⁺⁺ uptake associated with K⁺ depolarization was inhibited by relaxant doses of hydralazine; however, hydralazine did not significantly affect the rate of ⁴⁵Ca⁺⁺ efflux. Hydralazine also raised the threshold to the inhibitory (relaxant) effects of higher (>2.5 mM) bath concentrations of Ca⁺⁺. It is suggested that hydralazine inhibits K⁺ contractures in aortic strips by interference with the entry of Ca⁺⁺ into the cell, reflecting an effect of hydralazine at the cell surface membrane.

Original language	English
Pages (from-to)	40-48
Number of pages	9
Journal	Journal of Pharmacology and Experimental Therapeutics
Volume	207
Issue number	1
State	Published - 1 Dec 1978

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title = "Interaction of hydralazine with tension development and mechanisms of calcium accumulation in K+-stimulated rabbit aortic strips",

abstract = "A study was made of the effects of hydralazine on K+ contractures in rabbit aortic strips. Measurements were made of effects on tension generation, Ca++ accumulation measured using 45Ca++ (lanthanum method) and 45Ca++ efflux. Hydralazine relaxed established K+ contractures and inhibited tension development when tissue exposure to hydralazine preceded K+ depolarization. Both the threshold and the maximum tension responses of strips to Ca++ (K+-depolarized tissues) were altered by hydralazine in a dose-dependent manner. The Ca++ uptake associated with K+ depolarization was inhibited by relaxant doses of hydralazine; however, hydralazine did not significantly affect the rate of 45Ca++ efflux. Hydralazine also raised the threshold to the inhibitory (relaxant) effects of higher (>2.5 mM) bath concentrations of Ca++. It is suggested that hydralazine inhibits K+ contractures in aortic strips by interference with the entry of Ca++ into the cell, reflecting an effect of hydralazine at the cell surface membrane.",

author = "McLean, {A. J.} and {Du Souich}, P. and Barron, {K. W.} and Briggs, {A. H.}",

year = "1978",

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T1 - Interaction of hydralazine with tension development and mechanisms of calcium accumulation in K+-stimulated rabbit aortic strips

AU - McLean, A. J.

AU - Du Souich, P.

AU - Barron, K. W.

AU - Briggs, A. H.

PY - 1978/12/1

Y1 - 1978/12/1

N2 - A study was made of the effects of hydralazine on K+ contractures in rabbit aortic strips. Measurements were made of effects on tension generation, Ca++ accumulation measured using 45Ca++ (lanthanum method) and 45Ca++ efflux. Hydralazine relaxed established K+ contractures and inhibited tension development when tissue exposure to hydralazine preceded K+ depolarization. Both the threshold and the maximum tension responses of strips to Ca++ (K+-depolarized tissues) were altered by hydralazine in a dose-dependent manner. The Ca++ uptake associated with K+ depolarization was inhibited by relaxant doses of hydralazine; however, hydralazine did not significantly affect the rate of 45Ca++ efflux. Hydralazine also raised the threshold to the inhibitory (relaxant) effects of higher (>2.5 mM) bath concentrations of Ca++. It is suggested that hydralazine inhibits K+ contractures in aortic strips by interference with the entry of Ca++ into the cell, reflecting an effect of hydralazine at the cell surface membrane.

AB - A study was made of the effects of hydralazine on K+ contractures in rabbit aortic strips. Measurements were made of effects on tension generation, Ca++ accumulation measured using 45Ca++ (lanthanum method) and 45Ca++ efflux. Hydralazine relaxed established K+ contractures and inhibited tension development when tissue exposure to hydralazine preceded K+ depolarization. Both the threshold and the maximum tension responses of strips to Ca++ (K+-depolarized tissues) were altered by hydralazine in a dose-dependent manner. The Ca++ uptake associated with K+ depolarization was inhibited by relaxant doses of hydralazine; however, hydralazine did not significantly affect the rate of 45Ca++ efflux. Hydralazine also raised the threshold to the inhibitory (relaxant) effects of higher (>2.5 mM) bath concentrations of Ca++. It is suggested that hydralazine inhibits K+ contractures in aortic strips by interference with the entry of Ca++ into the cell, reflecting an effect of hydralazine at the cell surface membrane.

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