Figure 8. Vasoconstriction and dilatation of RMCAs by linopirdine and S-1 at a constant pressure of 80 mmHg.

A, representative recording of RMCA diameter during a pressure step from 10 to 80 mmHg in control conditions. B, representative recording of RMCA diameter during a pressure step from 10 to 80 mmHg followed by subsequent sequential exposure to 1 μm linopirdine and zero Ca²⁺ solution (i.e. no added Ca²⁺ and 2 mm EGTA). Dashed line represents the passive diameter of the vessel in 0 Ca²⁺ solution at 80 mmHg. C, representative recording of RMCA diameter during a pressure step from 10 to 80 mmHg followed by subsequent sequential exposure to 3, 10 and 20 μm S-1 and zero Ca²⁺ solution. Dashed line represents the passive diameter of the vessel in 0 Ca²⁺ solution at 80 mmHg. Note concentration-dependent vasodilatation by S-1. D, representative recording of RMCA diameter at 80 mmHg during sequential exposure to 30 nm ScTx1 followed by S-1 (20 μm) and zero Ca²⁺ solution. Dashed line represents the passive diameter of the vessel in 0 Ca²⁺ solution at 80 mmHg. Note the reversal of ScTx1-induced vasoconstriction by S-1.