Fig. 6. Representative traces showing the effects of intracellular alkalosis (addition of 40 mmol l^–1 NH₄Cl) and acidosis (removal of NH₄Cl) on tension of KCl (50 mmol l^–1)- and U-46619-contracted efferent branchial arteries in Hepes buffer. Two NH₄Cl exposures, 10 and 30+ min, are shown. Intracellular alkalosis contracts, and acidosis relaxes, KCl-stimulated vessels; these responses are reversed when the vessels are pre-contracted with U-46619. Vertical scale bars = 1 g.