Altered contractile responses of arteries from spontaneously hypertensive rat: The role of endogenous mediators and membrane depolarization.
Life Sci
; 166: 46-53, 2016 Dec 01.
Article
en En
| MEDLINE
| ID: mdl-27721001
ABSTRACT
AIMS:
The goal of our study was to reveal the important mechanism(s) responsible for the enhanced contractility of isolated arteries from animals suffering genetic hypertension. MAINMETHODS:
Contractile force of endothelium-denuded arteries, modulated by various interventions, was measured by wire myography. KEYFINDINGS:
Spontaneously hypertensive rat (SHR) and Wistar-Kyoto rat (WKY) arteries were stimulated by norepinephrine, increased extracellular K+ or tyramine. Strain difference was not observed in the contraction elicited by exogenous norepinephrine but SHR arteries responded more to tyramine (causing endogenous norepinephrine release from neuronal varicosities). K+-induced contraction was enhanced in SHR arteries, with no involvement of endogenous catecholamines. The α-adrenoceptor blockade lowered tyramine-induced contraction more in SHR arteries; similar effect was achieved by guanethidine-induced sympathectomy. Partial depolarization of WKY arteries by 20mM K+ enhanced its contraction to SHR level. The blockade of ß-adrenoceptors by propranolol or selective ß2-antagonist ICI-118,551 induced contraction of SHR endothelium-denuded arteries but was without significant effects on WKY arteries unless they were stimulated with K+. Both tyramine-induced and propranolol-induced contractions were attenuated by flupirtine and abolished by nifedipine.SIGNIFICANCE:
The differences of SHR and WKY arteries were not related to vascular expression of α- and ß-adrenoceptors or G-proteins. Enhanced contractility of SHR arteries is related to both increased presence of endogenous norepinephrine in vascular wall and also to altered vascular smooth muscle membrane potential.Palabras clave
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Base de datos:
MEDLINE
Asunto principal:
Arterias
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Ratas Endogámicas SHR
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Vasoconstricción
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Músculo Liso Vascular
Idioma:
En
Revista:
Life Sci
Año:
2016
Tipo del documento:
Article