Effects of noradrenaline on cytosolic concentrations of Ca(2+) in cultured corpus cavernosum smooth muscle cells of the rabbit.
An immunohistochemical examination of cultured corpus cavernosum cells of the rabbit showed that they were composed of many smooth muscle cells retaining -smooth muscle actin and a few of endothelial cells. Application of noradrenaline (NA, 0.5-100 microM) to the culture dose-dependently increased cytosolic concentrations of Ca2+ ([Ca2+]i) in smooth muscle cells. The NA (10 microM)-induced [Ca2+]i increase was dose-dependently inhibited by phenoxybenzamine (1 nM-1 microM). The inhibition was 71% at 0.1 microM and was completely made at 1 microM. An alpha(1)-adrenoceptor antagonist, prazosin (0.1 microM), inhibited the [Ca2+]i response by 42%, and propranolol (1 microM) enhanced the response by 118%. These adrenoceptor antagonists showed almost the same effects on a contractile response of corporal tissue strips to NA (10 microM) as the effects on the [Ca2+]i response. Our results suggest that NA-induced [Ca2+]i increase was mixed with a large increase through 1-adrenoceptors and a small decrease through beta-adrenoceptors. The increased [Ca2+]i could play a role of intracellular messenger for leading to contraction of cavernosal smooth muscle cells.
Sato
Minoru
M
Department of Physiology, Akita University School of Medicine, 1-1-1 Hondo, Akita 010-8543, Japan. minoru@med.akita-u.ac.jp
Kawatani
Masahito
M
D000199:Actins / Q000378:metabolism; D058646:Adrenergic alpha-1 Receptor Agonists; D058668:Adrenergic alpha-1 Receptor Antagonists; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D005455:Fluorescent Antibody Technique; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000294:innervation / Q000378:metabolism*; D009638:Norepinephrine / Q000378:metabolism* / Q000494:pharmacology; D010410:Penile Erection / Q000187:drug effects / Q000502:physiology; D010413:Penis / Q000098:blood supply* / Q000166:cytology / Q000294:innervation*; D010643:Phenoxybenzamine / Q000494:pharmacology; D011224:Prazosin / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D011817:Rabbits; D018340:Receptors, Adrenergic, alpha-1 / Q000378:metabolism; D011943:Receptors, Adrenergic, beta / Q000187:drug effects / Q000378:metabolism; D017779:Sympathetic Fibers, Postganglionic / Q000378:metabolism*
D000199:Actins; D058646:Adrenergic alpha-1 Receptor Agonists; D058668:Adrenergic alpha-1 Receptor Antagonists; D000317:Adrenergic alpha-Antagonists; D000319:Adrenergic beta-Antagonists; D018340:Receptors, Adrenergic, alpha-1; D011943:Receptors, Adrenergic, beta; D010643:Phenoxybenzamine; D011433:Propranolol; D002118:Calcium; D009638:Norepinephrine; D011224:Prazosin