Both the net effects and the mechanisms of action of intracellular pH (pHi) perturbations upon vascular tone have been investigated. pHi was modified using two procedures; NH4Cl application and withdrawal (NH4Cl pulse) and organic salt application. NH4Cl application and its subsequent withdrawal have been found to produce intracellular alkalinity and acidity, respectively, in various non-vascular (Roos and Boron, 1981; Thomas, 1984) as well as vascular tissues (Spurway and Wray, 1987). Application of weak organic salts has been found to decrease pHi in various tissues (Roos and Boron, 1981). Most experiments concerned with mechanism were carried out on one or both of two preparations: the rabbit ear vascular bed perfused through its central artery and the isolated perfused rat tail artery, each activated with NA, at about 2
