The effects of H1- and H2-receptor blocking agents on postsynaptic potentials recorded from the bull-frog sympathetic ganglion.
The effects of H1-blockers (pyrilamine, diphenhydramine and promethazine) and H2-blockers (cimetidine, ranitidine) on the postsynaptic potentials of the bull-frog sympathetic ganglion were studied by means of the sucrose gap method. All the H1-blockers tested, at concentrations of 10(-6)-10(-4) M, depressed the amplitudes of both action and slow postsynaptic potentials in positive and negative directions in a concentration-dependent manner; these drugs had more potent inhibitory effects on postsynaptic potentials. In the case of H2-blockers, action and postsynaptic potentials were slightly depressed as perfusion continued at 10(-4) M. From the present experiments, it was concluded that H1-blockers directly inhibit postsynaptic potentials of the sympathetic ganglions, and that this inhibition may be responsible for various autonomic disturbances attributed to H1-blockers.
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D005728:Ganglia, Sympathetic / Q000187:drug effects* / Q000502:physiology; D006634:Histamine H1 Antagonists / Q000494:pharmacology*; D006635:Histamine H2 Antagonists / Q000494:pharmacology*; D007552:Isotonic Solutions; D009538:Nicotine / Q000494:pharmacology; D010042:Ouabain / Q000494:pharmacology; D011892:Rana catesbeiana; D000077331:Ringer's Solution
D006634:Histamine H1 Antagonists; D006635:Histamine H2 Antagonists; D007552:Isotonic Solutions; D010042:Ouabain; D009538:Nicotine; D001285:Atropine; D000077331:Ringer's Solution