Abstract
Constant current pulses have been applied to single muscle fibers of the barnacle, Balanus nubilus Darwin, with an axial metal electrode. The membrane potential change, which took place over a large part of the muscle fiber, was measured with a similar electrode. Depolarizing pulses, if the voltage was greater than threshold, produced tension. The size of the tension was a function of the magnitude and the duration of the depolarizing pulses. The latency between the onset of depolarization and tension can be only in part attributable to mechanical factors. AC stimulation produced tension, but 5 to 10 seconds were required for the steady-state level of the tension to be reached. Muscles were depolarized in elevated K and studied after the contracture had terminated. If not too depolarized, further depolarization produced tension. Termination of hyperpolarizing pulses also produced tension, which decayed quite slowly. Hyperpolarizing pulses reduced, or abolished, any preexisting tension. Thus, it appears that at certain values of the membrane potential tension is set up, but there is also a slow process of accommodation present.
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Selected References
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- CALDWELL P. C., WALSTER G. STUDIES ON THE MICRO-INJECTION OF VARIOUS SUBSTANCES INTO CRAB MUSCLE FIBRES. J Physiol. 1963 Nov;169:353–372. doi: 10.1113/jphysiol.1963.sp007261. [DOI] [PMC free article] [PubMed] [Google Scholar]
- CURTIS B. A. Some effects of Ca-free choline-Ringer solution on frog skeletal muscle. J Physiol. 1963 Apr;166:75–86. doi: 10.1113/jphysiol.1963.sp007091. [DOI] [PMC free article] [PubMed] [Google Scholar]
- HAGIWARA S., CHICHIBU S., NAKA K. I. THE EFFECTS OF VARIOUS IONS ON RESTING AND SPIKE POTENTIALS OF BARNACLE MUSCLE FIBERS. J Gen Physiol. 1964 Sep;48:163–179. doi: 10.1085/jgp.48.1.163. [DOI] [PMC free article] [PubMed] [Google Scholar]
- HAGIWARA S., NAKA K. I. THE INITIATION OF SPIKE POTENTIAL IN BARNACLE MUSCLE FIBERS UNDER LOW INTRACELLULAR CA++. J Gen Physiol. 1964 Sep;48:141–162. doi: 10.1085/jgp.48.1.141. [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]
- HOYLE G., SMYTH T., Jr NEUROMUSCULAR PHYSIOLOGY OF GIANT MUSCLE FIBERS OF A BARNACLE, BALANUS NUBILUS DARWIN. Comp Biochem Physiol. 1963 Dec;10:291–314. doi: 10.1016/0010-406x(63)90229-9. [DOI] [PubMed] [Google Scholar]
- ORKAND R. K. The relation between membrane potential and contraction in single crayfish muscle fibres. J Physiol. 1962 Apr;161:143–159. doi: 10.1113/jphysiol.1962.sp006878. [DOI] [PMC free article] [PubMed] [Google Scholar]