Fig. 1. Increases in porcine coronary arteriolar diameter (n = 22; baseline ID, 75 ± 4 μm) after administration of varying concentrations of isoflurane (0.16–0.75 mm; 0.5–2.5 MAC). Maximal dilation (34 ± 3 μm) was determined by exposing each vessel to 10−4m sodium nitroprusside. Vertical bars represent 1 ± SEM. Asterisks indicate a significant (P < 0.05) increase in arteriolar ID as compared with vessels before isoflurane exposure.