Abstract
The actions and the structure-activity relationship of alkylguanidines on the smooth muscle organs were investigated and the following results were obtained. On guinea-pig hypogastric nerve-vas deferens preparation and trachea preparation, the responses induced by the electrical stimulation of the nerve were potentiated with guanidine (G), methylguanidine (MG), N, N-dimethylguanidine (NN-DMG) and N, N'-dimethylguanidine (NN'-DMG), were not affected with ethylguanidine (EG) and were inhibited with propylguanidine (PG), butylguanidine (BG) and hexylguanidine (HG), in doses of 10-5-5×10-3M respectively. Also, the contractions of the vas deferens preparation induced by norepinephrine were potentiated with EG, PG, BG and HG, but the contractions induced by acetylcholine were not potentiated with these compounds. The contractions of the cat nictitating membrane induced by the electrical stimulation of the cervical sympathetic nerve were not affected by all compounds. In anaesthetized cats and rats, G, MG, NN-DMG and NN'-DMG, in dose of 5 mg/kg, produced a rise in the blood pressure. The rising actions induced by these compounds were not abolished with an adrenergic α-blockade. EG, PG, BG and HG, in dose of 5mg/kg, produced a temporary fall followed by a rise. These compounds potentiated the pressor action of norepinephrine and suppressed that of tyramine with the increase of the carbon number. In spinal cats, a temporary fall of the blood pressure induced by these compounds were abolished and only a rise was observed. Also, the fall action in the blood pressure and the increase of the heart rate induced by isoproterenol were suppressed with HG. HG (1%) had local anaesthetic action as potent as procaine, and its action was more lasting than that of procaine.
