The effect of temperature and mechanical work load on the intracellular pH and buffer capacity of cardiac muscle in rats.

The effect of temperature on hydrogen ions and buffer capacity in extracellular fluid differs from the effects in intracellular fluid. In our experiments cardiac hypertrophy was achieved by increasing the mechanical work load. It could be demonstrated that there is a certain correlation between buffering of hydrogen ions and mechanical activity of heart muscle.

Intracellular pH in unanesthetized dogs during panting.

Intracellular pH, arterial blood gases and several plasma enzymes were estimated in unanesthetized dogs during a 3-hour exposure to 30 degrees C/50% relative humidity, and 40 degrees C/50% relative humidity. No change occurred during mild heat stress, whereas during severe heat stress a profound respiratory alkalosis developed together with an increase in intracellular pH from 7.03 to 7.

Determination of mean whole body intracellular pH in unanesthetized dogs.

In order to determine mean whole body pHi in unanesthetized dogs, assumptions on the urinary and intestinal excretion of DMO, the total loss of an injected single dose of [14C] DMO, and the distribution kinetics of DMO were tested experimentally. Urinary excretion of DMO was almost negligible. The best assumption on the total loss of DMO was based on the exponential decay observed over a period of 1 to 4 weeks.