Response of the portal vein of spontaneous hypertensive rats to intracellular pH.

ABSTRACT

The effect of intracellular pH perturbations on the portal vein preparations of spontaneously hypertensive rats and their control Wistar Kyoto rats was investigated. Intracellular alkalinity induced by application of 20 mM NH4Cl or 20 mM trimethylamine produced dilatation of both preparations. Intracellular acidity induced by washout of the previous ammonium and trimethylamine solutions or by application of 20 mM sodium propionate solution caused constriction of both preparations. These responses of the portal veins of both animals to intracellular pH variations were qualitatively the same in nonactivated preparations and in preparations precontracted with 26 mM K+ or 1 microM norepinephrine. Recovery from acidic constrictions induced by washout of ammonium and trimethylamine solutions was significantly slower in spontaneous hypertensive rats than in Wistar Kyoto rats preparations. Conceivably, a lower intracellular pH in the vascular smooth muscle of the resistance vessels of hypertensive patients, as compared to normotensive individuals, may partly account for the hypertensive phenomena.