Abstract
Systemic blood pressure of dogs anesthetized with amobarbital sodium decreased transiently following intravenous injections of guaiacol glycerol ether mononicotinate (GGEMN) (0.3 to 10mg/kg). Treatment with atropine, hexamethonium, diphenhydramine and propranolol did not inhibit the hypotenisve effect of GGEMN. Carotid and femoral blood flow of anesthetized dogs was increased by intravenous (0.3 to 3.0mg/kg) and intraarterial injections (3 to 30μg/kg) of GGEMN in a dose-dependent manner. The flow increase was not inhibited by atropine, tolazoline, hexamethonium and propranolol. Guaiacol glycerol ether (GGE), nicotinic acid and a mixture of these drugs were apparently less potent in increasing the blood flow than GGEMN. The heart rate and the ECG pattern of unanesthetized, restrained rabbits were not influenced by intravenous injections of GGEMN in doses up to 30mg/kg and by oral administrations of the drug in doses up to 10g/kg. The tension of spirally-cut strips of rabbit thoracic aortae and superior mesenteric arteries was significantly decreased by GGEMN (10-4 to 3×10-3g/ml). Treatment of aortic strips with GGEMN shifted the dose-contractile response curves of noradrenaline and Ba++ to the right and downward. Contractile responses of aortic strips to transmural electrical stimulation were inhibited by GGEMN. The rate and the contratile force of isolated rabbit atria were not influenced by GGEMN in concentrations lower than 10-4g/ml but moderately reduced at 3×10-4g/ml. It may be concluded that an increase in the peripheral blood flow by GGEMN is due to a decrease in the peripheral vascular resistance, which would not be asso-ciated with interference with autonomic innervation but with direct (papaverine-like) actions on vascular smooth muscles. It appears that GGEMN is markedly less cardiotoxic than papaverine.
