Abstract
It has been observed that the vasodepressor action of Iso was reversed to vasopression by ergotamine in cats under thiopental-barbital anesthesia, but no reversal was found under urethan g anesthesia, in spite of the finding that the pressor action of Epi was depressed or reversed. Consequently, barbiturates seem to be activating agents in producing the Iso-reversal.
When an isolated dog's hind leg was perfused artificially with the heparinized whole blood, the vasodilator action ot Iso could not be modified by ergotamine. Therefore, factors responsible for the reversal cannot be found in peripheral vascular beds.
