Figure 1. Effects of correolide (COR) and 4-aminopyridine (4-AP) on the resting V_m and diameter of rat small cerebral arteries.

A, microelectrode recordings of V_m in a rat middle cerebral artery indicate a resting V_m level of about −57 mV. B, the addition of 1 μM correolide (COR) induced a pronounced depolarization to about −34 mV (top trace). COR induced action potentials in another artery (bottom trace). C, the final addition of 1 mM 4-AP did not induce further depolarization. D and E, average V_m and diameter values for cerebral arteries from six rats exposed to 1 μM COR, and subsequently, exposed to both 1 μM COR and 1 mM 4-AP. Data are expressed as means ±s.e.m. (n = 6). * Significant difference (P < 0.05) between control and experimental values.