Fig. 4.

Simultaneous contractile tension and intracellular free Ca²⁺ to physiological saline solution, 0.3, 0.6, 1, and 3 nM of endothelin-1. A: experimental protocol depicting developed tension and intracellular free Ca²⁺ from arterial rings exposed to increasing concentrations of endothelin-1. Developed tension as a function of fura-2 ratio between nonoccluded and collateral-dependent arteries in sedentary (B) and exercise-trained (C) pigs. Best fit analysis was obtained for each data set using the Stirling equation: f = y0 + a·[exp(b·x)−1]/b (SPSS, SigmaPlot 9.0). B: sedentary pigs' best fit analysis was obtained with the same equation: y = 4.621 + 0.0003·[exp(8.383·x) − 1]/8.383. C: exercise-trained pigs' best fit analysis was obtained with different equations for nonoccluded {y = 5.302 + 2.58e-5·[exp(8.874·x) − 1]/8.874} vs. collateral-dependent {y = 5.302 + 2.58e-5·[exp(9.583·x) − 1]/9.583} arteries. *P < 0.05.