Possible involvement of ganglionic blocking effects of diltiazem in regulation of blood pressure and heart rate of the rabbit.
Under pentobarbitone anesthesia, arterial blood pressure and heart rate were recorded in rabbits. The elevation in systemic blood pressure and increased heart rate induced by electrical stimulation of the right thoracic sympathetic nerve trunk were depressed by either an intravenous injection of diltiazem (300 micrograms/kg) or by placing cotton pledgets soaked in 2 mM diltiazem solution onto the right stellate ganglion. These inhibiting effects of diltiazem were statistically significant with high sympathetic stimulation frequencies (10-20 Hz), but not when lower frequencies (1-5 Hz) were used. On the other hand, hexamethonium (10 mg/kg i.v. or 100 mM applied topically) depressed cardiovascular responses to sympathetic stimulation over a wide range of frequencies (1-20 Hz). Present results reveal a frequency-dependent inhibition of ganglionic transmission by diltiazem, and suggest that diltiazem may depress excessive sympathetic activity without affecting normal ganglionic transmission.
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D004110:Diltiazem / Q000494:pharmacology*; D005728:Ganglia, Sympathetic / Q000187:drug effects; D005730:Ganglionic Blockers / Q000494:pharmacology*; D006339:Heart Rate / Q000187:drug effects*; D007275:Injections, Intravenous; D011817:Rabbits; D013562:Sympathectomy; D014628:Vagotomy
D005730:Ganglionic Blockers; D004110:Diltiazem