Elevated aortic pressure, calcium uptake, and protein synthesis in rat heart

Elevation of aortic pressure from 60 to 120 mmHg increased the initial rate of 45Ca2+ uptake and the steady-state level that was achieved. The increase in uptake was as great after the first 10 min of pressure elevation as it was after aortic pressure had been at 120 mmHg for 1 h. When aortic pressure was returned to 60 mmHg for 30 min after 1 h at 120 mmHg, calcium uptake was restored to the control value. Elevation of perfusate Ca2+, from 0.5 mM to 2.9 and 5.0 mM increased oxygen consumption and decreased creatine phosphate/creatine ratios in hearts supplied glucose but had not effect on the rate of total protein synthesis. When hearts were supplied pyruvate to maintain high energy phosphates, an increase in perfusate Ca2+ from 0.5 to 2.9 mM did not accelerate total protein synthesis or ribosome formation. These studies provide no support for a role for extracellular Ca2+ availability in mediating the effects of elevated aortic pressure on total protein synthesis and ribosome formation.