Figure 8. Pretreatment with latrunculin B (LatB) abolishes the myogenic response and maintenance of phenylephrine (PE)-induced contraction in rat gracilis arteries (RGAs).

A, representative recording of RGA diameter during treatment with LatB (10 μmol l⁻¹) before a pressure step from 20 to 80 mmHg and subsequent exposure to zero Ca²⁺ saline. B, mean diameter ±s.e.m. of RGAs at 80 mmHg in the absence and presence of LatB or zero Ca²⁺ saline (n= 3). C, representative recording of RGA diameter during two applications of PE (10 μmol l⁻¹) at 20 mmHg, with the second treatment in the presence of LatB. D, mean diameter ±s.e.m. before and in PE in the absence and presence of LatB, with the latter expressed as diameter at maximal (peak or P) constriction and final, maintained diameter (sustained or S) (n= 5). E, representative traces of the recordings obtained in (C), showing the sustained constriction in response to PE alone and the dilation back to original diameter when PE was applied in the presence of LatB. *Significantly different (P < 0.05) from control value.