PT  - JOURNAL ARTICLE
AU  - M. R. LIPSIUS
AU  - M. J. SIEGMAN
AU  - C. Y. KAO
TI  - DIRECT RELAXANT ACTIONS OF PROCAINE AND TETRODOTOXIN ON VASCULAR SMOOTH MUSCLE
DP  - 1968 Nov 01
TA  - Journal of Pharmacology and Experimental Therapeutics
PG  - 60--74
VI  - 164
IP  - 1
4099  - http://jpet.aspetjournals.org/content/164/1/60.short
4100  - http://jpet.aspetjournals.org/content/164/1/60.full
SO  - J Pharmacol Exp Ther1968 Nov 01; 164
AB  - In head-body cross-perfused dogs, procaine caused systemic hypotension only when it was applied to the body, indicating that the hypotension was due to an action of procaine somewhere outside the brain. This conclusion is similar to an earlier one on the hypotension produced by tetrodotoxin. Using a gracilis muscle preparation with a vasculature isolated from the systemic circulation and perfused by a constant-volume pump with either the animal's own blood or another animal's blood, it was shown that small doses of procaine (1-5 mg/kg) and tetrodotoxin (0.5-0.8 µg/kg) caused a fall in the perfusion pressure. Since these doses did not block the reflex vasomotor effects on perfusion pressure caused by changes in systemic blood pressure or the effects of stimulating the sympathetic nerves, the fall in perfusion pressure was attributed to a direct relaxant effect on vascular smooth muscle. This conclusion is supported by the observations that after alpha or beta adrenergic blockade, or histamine blockade, the fall in perfusion pressure can still he produced by procaine and tetrodotoxin. © 1968, by The Williams & Wilkins Company