Yoshiya Horiguchi

The vasodilator action of formaldehyde in dogs.

The perfused hind legs of anesthetized dogs were used in investigations of the depressor effect of formaldehyde. An injection of formaldehyde into the right femoral vein caused a transient fall in systemic blood pressure and a one-step fall in perfusion pressure. The initial fall took place before the arrival of the drug in the perfused area. It was followed by a further decrease after the arrival of the drug in the area. Our study showed that dogs completely lack the pressor response to formaldehyde that rats have been reported to manifest. Though the initial fall in perfusion pressure was little affected by atropine or vagotomy, it was abolished by autonomic ganglion blocker, adrenergic neuron blocker, and a-adrenergic blocker. These results suggest that the initial decrease is caused by inhibition of the sympathetic nervous system. This in turn suggests that the depressor action of formaldehyde results from a combination of direct action on the cardiovascular system and inhibitory action on the sympathetic nervous system. The inhibition plays a smaller role in the depressor action than the vasodilator effect, because a-blockers in intact dogs augmented, rather than inhibited, the depressor effect.