Possible involvement of neuronal nitric oxide synthase enzyme in early-phase isoflurane-induced hypotension in rats.

This study was conducted to demonstrate the involvement of nitric oxide synthase (NOS) in the early-phase isoflurane-induced hypotension and to ascertain whether this NOS is neuronal NOS (nNOS) or endothelial NOS (eNOS). Mean arterial pressures (MAPs) were directly measured from the femoral arteries of urethane-anesthetized rats. Isoflurane-induced changes in MAP were monitored in rats following pretreatment with vehicle or one of the following NOS inhibitors: L-NG)monomethyl-L-arginine (L-NMMA), which is non-selective; L-NG)nitro arginine (L-NOARG), which is more selective for nNOS and eNOS; and 7-nitroindazole (7-NI), which is selective for nNOS.

An opioid basis for early-phase isoflurane-induced hypotension in rats.

This study was conducted to more clearly delineate the possible role of endogenous opioid receptors and opioid peptides in general anesthesia-associated hypotension in rats. Exposure to 2% isoflurane in oxygen produced a triphasic change in mean arterial pressure (MAP), including an early phase in which MAP fell by -28.4 +/- 2.