Abstract
1. In the smooth muscle of rabbit aorta, the relationship between the change in membrane potential and the concentration evoked by current application was studied. 2. In normal Krebs solution, outward current produced contraction when the membrane was depolarized to about -45 mV and the membrane resistance was decreased. Further increase in the outward current intensity produced an increase in tension development with very small additional depolarization but with a marked decrease in membrane resistance. 3. With arteries depolarized to about -20 mV, in excess K solution of concentration more than 60 mM, outward current failed to produce further contraction. However, contraction was produced when the inward current was switched off. This may be due to removal of an inactivation process by hyperpolarization of the membrane. 4. In excess K solution, no relaxation was observed with inward current application. However, when artificial stretch was applied to the preparation immersed in 98 mM-K solution, a prolonged hyperpolarizing current of more than 3 sec could cause relaxation. 5. Ca-free solution and Mn ion (0.5 mM) blocked the concentration induced by outward current. Phentolamine and tetrodotoxin had not effect. 6. It is suggested that increased membrane conductance associated with depolarization by outward current increased the Ca influx which causes contraction.
Full text
PDF












Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Atwater I., Dawson C. M., Ribalet B., Rojas E. Potassium permeability activated by intracellular calcium ion concentration in the pancreatic beta-cell. J Physiol. 1979 Mar;288:575–588. [PMC free article] [PubMed] [Google Scholar]
- Bolton T. B. Effects of stimulating the acetylcholine receptor on the current-voltage relationships of the smooth muscle membrane studied by voltage clamp of potential recorded by micro-electrode. J Physiol. 1975 Aug;250(1):175–202. doi: 10.1113/jphysiol.1975.sp011048. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Bolton T. B. Mechanisms of action of transmitters and other substances on smooth muscle. Physiol Rev. 1979 Jul;59(3):606–718. doi: 10.1152/physrev.1979.59.3.606. [DOI] [PubMed] [Google Scholar]
- Clusin W. T., Bennett M. V. Calcium-activated conductance in skate electroreceptors: voltage clamp experiments. J Gen Physiol. 1977 Feb;69(2):145–182. doi: 10.1085/jgp.69.2.145. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ebashi S., Endo M. Calcium ion and muscle contraction. Prog Biophys Mol Biol. 1968;18:123–183. doi: 10.1016/0079-6107(68)90023-0. [DOI] [PubMed] [Google Scholar]
- Gilly W. F., Hui C. S. Mechanical activation in slow and twitch skeletal muscle fibres of the frog. J Physiol. 1980 Apr;301:137–156. doi: 10.1113/jphysiol.1980.sp013195. [DOI] [PMC free article] [PubMed] [Google Scholar]
- HODGKIN A. L., HOROWICZ P. Potassium contractures in single muscle fibres. J Physiol. 1960 Sep;153:386–403. doi: 10.1113/jphysiol.1960.sp006541. [DOI] [PMC free article] [PubMed] [Google Scholar]
- KEATINGE W. R. MECHANISM OF ADRENERGIC STIMULATION OF MAMMALIAN ARTERIES AND ITS FAILURE AT LOW TEMPERATURES. J Physiol. 1964 Nov;174:184–205. doi: 10.1113/jphysiol.1964.sp007481. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Keatinge W. R. Ca concentration and flux in Ca-deprived arteries. J Physiol. 1972 Jul;224(1):35–59. doi: 10.1113/jphysiol.1972.sp009880. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Keatinge W. R. Ionic requirements for arterial action potential. J Physiol. 1968 Jan;194(1):169–182. doi: 10.1113/jphysiol.1968.sp008400. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Keatinge W. R. Proceedings: Extracellular Ca and response of sheep carotid artery to depolarization. J Physiol. 1976 Jun;258(2):73P–74P. [PubMed] [Google Scholar]
- Krnjević K., Lisiewicz A. Injections of calcium ions into spinal motoneurones. J Physiol. 1972 Sep;225(2):363–390. doi: 10.1113/jphysiol.1972.sp009945. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Kuriyama H., Mishima K., Suzuki H. Some differences in contractile responses of isolated longitudinal and circular muscle from the guinea-pig stomach. J Physiol. 1975 Oct;251(2):317–331. doi: 10.1113/jphysiol.1975.sp011095. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Mekata F. Current spread in the smooth muscle of the rabbit aorta. J Physiol. 1974 Oct;242(1):143–155. doi: 10.1113/jphysiol.1974.sp010698. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Mekata F. Electrophysiological studies of the smooth muscle cell membrane of the rabbit common carotid artery. J Gen Physiol. 1971 Jun;57(6):738–751. doi: 10.1085/jgp.57.6.738. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Mekata F. Rectification in the smooth muscle cell membrane of rabbit aorta. J Physiol. 1976 Jun;258(2):269–278. doi: 10.1113/jphysiol.1976.sp011419. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Miledi R., Parker I., Schalow G. Calcium transients in frog slow muscle fibres. Nature. 1977 Aug 25;268(5622):750–752. doi: 10.1038/268750a0. [DOI] [PubMed] [Google Scholar]
- Noble D., Stein R. B. The threshold conditions for initiation of action potentials by excitable cells. J Physiol. 1966 Nov;187(1):129–162. doi: 10.1113/jphysiol.1966.sp008079. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Vassort G. Voltage-clamp analysis of transmembrane ionic currents in guinea-pig myometrium: evidence for an initial potassium activation triggered by calcium influx. J Physiol. 1975 Nov;252(3):713–734. doi: 10.1113/jphysiol.1975.sp011167. [DOI] [PMC free article] [PubMed] [Google Scholar]
