Fig 1. Impact of calcium on the hydrolysis of pyrophosphate and ATP.

Rat aortic ring tissue samples were incubated ex vivo in sHBSS (supplemented with 0.9 mmol/L magnesium) with 1 mmol/L calcium (+CaCl₂) or without calcium (-CaCl₂). (A) Representative time course for the hydrolysis of 5 μmol/L PPi (and 10 μCi/mL ³²PPi as radiotracer) measured by Pi release (³²Pi). (B) Representative time course of the hydrolysis of 1 μmol/L ATP (and 10 μCi/mL [γ³²P]ATP as radiotracer) measured by Pi release (γ³²Pi). Results in (C) and (D) are means ± SEM, after 10 min of incuation, of three independent experiments, with a total of 20 rings per condition (10 different rats). Student’s t-test was used for statistical analysis. ***p <0.001.