Inhibition by diltiazem of norepinephrine release from sympathetic nerves in the rabbit pulmonary artery.
In order to determine if the calcium blocker diltiazem could alter excitation-secretion coupling in vascular sympathetic nerves, superfused rabbit pulmonary arterial strips were preincubated with 3H-norepinephrine and stimulated electrically (2-8 Hz) and by KCl (60 mM). Diltiazem significantly inhibited tension development with 4 Hz (1.5 X 10(-5) M) and 8 Hz (1.5 X 10(-6), 1.5 X 10(-5) M) stimuli, but only at 1.5 X 10(-5) M did diltiazem inhibit the 3H overflow evoked by an 8-Hz stimulus. No inhibition of 3H overflow was noted with the 2 and 4 Hz stimuli. With an 8-Hz stimulus the inhibition of tension development (45.4%) by diltiazem (1.5 X 10(-5) M) was significantly greater than the inhibition of 3H overflow (33.8%). A similar relationship was noted with 60 mM KCl stimulation. These data suggest that excitation-secretion coupling in vascular sympathetic nerves can be inhibited by diltiazem.
D000818:Animals; D001552:Benzazepines / Q000494:pharmacology*; D003000:Clonidine / Q000494:pharmacology; D003864:Depression, Chemical; D004110:Diltiazem / Q000494:pharmacology*; D004347:Drug Interactions; D004558:Electric Stimulation; D066298:In Vitro Techniques; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism*; D009638:Norepinephrine / Q000378:metabolism*; D011189:Potassium Chloride / Q000494:pharmacology; D011651:Pulmonary Artery / Q000378:metabolism; D011817:Rabbits; D013564:Sympathetic Nervous System / Q000378:metabolism*; D013997:Time Factors
D001552:Benzazepines; D011189:Potassium Chloride; D004110:Diltiazem; D003000:Clonidine; D009638:Norepinephrine