Role of neuronal and vascular Ca2+- channels in the ACTH-induced reversal of haemorrhagic shock.

1 In a rat model of volume-controlled haemorrhagic shock causing the death of all control (saline-treated) animals within 30 min, the intravenous (i.v.) bolus injection of ACTH-(1-24) at a dose. of 160 mug kg-1 produced an impressive and sustained restoration of arterial pressure, pulse pressure and respiratory function, with 100% survival at the end of the observation period (2 h). 2 Both intracerebroventricular (i.c.v., 0.015-0.06 mug kg-1) and i.v. (5 mug kg-1) pretreatment with the N-calcium channel blocker, omega-onotoxin GVIA, and i.v. (but not i.c.v.) pretreatment with the L-calcium channel blocker, nicardipine (125-500 mug kg-1) dose-dependently prevented the ACTH-induced shock reversal. 3 These results further indicate that the effect of ACTH in haemorrhagic shock may involve a neuronal link and the eventual restoration of vascular tone mediated by N- and L-type calcium channels, respectively