Effects of tubocurarine on plasma histamine concentration in the rat. Correlation with the release of histamine from isolated mast cells.

The administration of tubocurarine i.v. in man produces hypotension, probably as a result of the release of histamine. The mechanisms involved in this action of tubocurarine on the plasma histamine concentration in rats, and on the isolated peritoneal mast cells were investigated. I.v. injections of tubocurarine (greater than 5 mg kg-1; corresponds to tubocurarine 4 X 10(-4) mol litre-1 in the plasma of the rats) evoked a phasic increase in plasma histamine concentration. In vitro studies showed that tubocurarine 4 X 10(-4) mol litre-1 released about 20% of the histamine contained in the isolated mast cells. Treatment of the mast cells with carbachol or atropine evoked no histamine release, nor did it modify the tubocurarine-induced release of histamine. These results suggest that the increased histamine concentrations in the plasma are attributable to an action of tubocurarine on the mast cells which is not mediated through the acetylcholine receptors distributed on these cells.