Torasemide inhibits angiotensin II-induced vasoconstriction and intracellular calcium increase in the aorta of spontaneously hypertensive rats
Palabras clave : 
Angiotensin II
Calcium
Furosemide
Irbesartan
Muscle, smooth, vascular
Rats, inbred SHR
Torasemide
Fecha de publicación: 
1999
Editorial : 
American Heart Association
ISSN: 
1524-4563
Cita: 
Fortuño A, Muñiz P, Ravassa S, Rodríguez JA, Fortuño MA, Zalba G, et al. Torasemide inhibits angiotensin II-induced vasoconstriction and intracellular calcium increase in the aorta of spontaneously hypertensive rats. Hypertension 1999 Jul;34(1):138-143.
Resumen
Torasemide is a loop diuretic that is effective at low once-daily doses in the treatment of arterial hypertension. Because its antihypertensive mechanism of action may not be based entirely on the elimination of salt and water from the body, a vasodilator effect of this drug can be considered. In the present study, the ability of different concentrations of torasemide to modify angiotensin II (Ang II)-induced vascular responses was examined, with the use of an organ bath system, in endothelium-denuded aortic rings from spontaneously hypertensive rats. Ang II-induced increases of intracellular free calcium concentration ([Ca(2+)](i)) were also examined by image analysis in cultured vascular smooth muscle cells (VSMCs) from spontaneously hypertensive rats. A dose-response curve to Ang II was plotted for cumulative concentrations (from 10(-9) to 10(-6) mol/L) in endothelium-denuded aortic rings (pD(2)=7.5+/-0.3). Isometric contraction induced by a submaximal concentration of Ang II (10(-7) mol/L) was reduced in a dose-dependent way by torasemide (IC(50)=0.5+/-0.04 micromol/L). Incubation of VSMCs with different concentrations of Ang II (from 10(-10) to 10(-6) mol/L) resulted in a dose-dependent rise of [Ca(2+)](i) (pD(2)=7.5+/-0.3). The stimulatory effect of [Ca(2+)](i) induced by a submaximal concentration of Ang II (10(-7) mol/L) was blocked by torasemide (IC(50)=0.5+/-0.3 nmol/L). Our findings suggest that torasemide blocks the vasoconstrictor action of Ang II in vitro. This action can be related to the ability of torasemide to block the increase of [Ca(2+)](i) induced by Ang II in VSMCs. It is proposed that these actions might be involved in the antihypertensive effect of torasemide observed in vivo.

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1999 Fortuño Hypertension.pdf
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