The possible role of catecholamines in the protective effect of general anesthetics against kidney lesions in rats subjected to hemorrhagic hypotension.

Dibenamine, 15 mg/kg, injected i.p. in rats anesthetized with ketamine, 60 min before bleeding for 60 min against 40 mm Hg, significantly reduced the severity of kidney lesions. The maximum bleeding volume was reduced by 14%. Adrenalectomy also reduced the bleeding volume but all animals died within 24 hr. In unanesthetized rats bled against 40 mm Hg, plasma adrenaline and nor-adrenaline rose approximately tenfold as compared with unbled animals. Comparable marked increases in plasma adrenaline and somewhat smaller increases in plasma nor-adrenaline were observed after bleeding rats anesthetized with ketamine and ethylurethane, anesthetics which protect only slightly against the occurrence of kidney lesions. The rise in plasma adrenaline and nor-adrenaline was significantly lower after bleeding rats anesthetized with the highly protective anesthetics Na-pentobarbital, halothane and methoxyflurane. If, however, rats anesthetized with Na-pentobartical were bled for 40 min against 25 mm Hg, a situation in which the occurrence of kidney lesions is not prevented, the plasma concentration of both catecholamines was as high as in unanesthetized rats bled against 40 mm Hg. It is concluded that vasoconstriction due to the release of catecholamines is an important factor in the generation of kidney lesions during hypotension in rats and that the protective effect of a number of general anesthetics largely depends on their ability to suppress the release of catecholamines.