Noradrenaline modulation of calcium channels in single smooth muscle cells from rabbit ear artery

• Published in: The Journal of physiology Vol. 404; no. 1; pp. 767 - 784
• Main Authors: Benham, C D, Tsien, R W
• Format: Journal Article
• Language: English
• Published: Oxford The Physiological Society 01.10.1988; Blackwell
• Subjects: Animals; arteries; Biological and medical sciences; Blood vessels and receptors; calcium; Calcium Channel Agonists - pharmacology; Calcium Channel Blockers - pharmacology; Calcium Channels - physiology; Dihydropyridines - pharmacology; Dose-Response Relationship, Drug; Evoked Potentials - drug effects; Fundamental and applied biological sciences. Psychology; Guanosine Triphosphate - pharmacology; In Vitro Techniques; Muscle Contraction - drug effects; Muscle, Smooth, Vascular - physiology; norepinephrine; Norepinephrine - pharmacology; Phenylephrine - pharmacology; Rabbits; Receptors, Adrenergic - physiology; smooth muscle; Vertebrates: cardiovascular system; Transmembrane current; Vertebrata; Regulation(control); Mammalia; Calcium; Blood vessel; Electrophysiology; Rabbit; Norepinephrine; Circulatory system; Lagomorpha
• ISSN: 0022-3751; 1469-7793
• DOI: 10.1113/jphysiol.1988.sp017318

1. Whole-cell recordings of voltage-gated Ca2+ current in single smooth muscle cells from rabbit ear artery were obtained with 110 mM-Ba2+ as charge carrier. 2. Noradrenaline (NA, 1-20 microM) produced a sustained increase in the dihydropyridine-sensitive L-type Ca2+ current, ranging up to 3-fold in some cells. The dihydropyridine-resistant T-type Ca2+ current was not affected. 3. The time and voltage dependence of activation and inactivation of the L-type current were not significantly changed during NA modulation. 4. The NA-induced increase in L-current was enhanced in magnitude and consistency by the inclusion of 200 microM-GTP in the pipette (internal) solution. 5. The effect of NA on L-current was not abolished by pre-treatment with prazosin, phentolamine or propranolol, suggesting that it is not mediated by alpha- or beta-adrenoceptors. 6. Phenylephrine (5 microM) was ineffective as an agonist, while adrenaline was approximately equipotent to NA. In these respects, the pharmacology of L-current modulation resembles that of 'gamma'-adrenergic receptors (Hirst & Nield, 1980). 7. NA modulation of L-type Ca2+ channels may be particularly important in promoting sympathetic vasoconstriction in resistance vessels where Ca2+ stores are relatively poorly developed and where NA-evoked contractions are very sensitive to organic Ca2+ channel antagonists.