The effects of long-standing hypertensive left ventricular hypertrophy on intracellular pH and intracellular electrolytes in rats.

Experiments were performed to assess the effect of long-standing (4-8 weeks) left ventricular hypertrophy (induced by experimental hypertension) on intracellular pH (pHi) and intracellular electrolytes in left ventricular tissue. They were undertaken on: (1) hypertensive rats (hypertension being induced by either (a) subdiaphragmatic aortic constriction, (b) unilateral renal artery clipping, or (c) unilateral renal artery clipping with contralateral nephrectomy); (2) sham-operated rats for the above 3 subgroups; and (3) control (unoperated) rats. In this study the hypertension (and therefore the hypertrophy) was of long (4-8 weeks) duration. Intracellular pH and intracellular electrolytes were measured in left ventricular, right ventricular and skeletal muscle tissue from these animals. Intracellular pH control was assessed by exposing a number of animals in each group to a respiratory acidosis (by varying the concentration of inspired PCO2). As described previously [Oldershaw PJ, Cameron IR, Int J Cardiol 1988;18:131-141], in the earlier stages of left ventricular hypertrophy (1-4 weeks duration) left ventricular pHi was significantly alkaline at normal levels of extracellular pH. At this late stage, with the exception of animals with aortic constriction, pHi had returned to control values. There was no change in resting levels of pHi in right ventricular or skeletal muscle tissue in any hypertensive group. The improved control of pHi in left ventricular tissue observed with hypertrophy of short duration (1-4 weeks [Oldershaw PJ, Cameron IR. Int J Cardiol 1988;18:131-141]) persisted in all experimental groups at this stage (4-8 weeks) after the onset of development of left ventricular hypertrophy. There was no change in pHi control in right ventricular or skeletal muscle tissue. Neither was there any change in intracellular electrolyte concentrations or content in association with hypertension in any tissue or group studied.