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The electro physiology of single smooth muscle cells isolated from the ctenophore mnemiopsis


, : The electro physiology of single smooth muscle cells isolated from the ctenophore mnemiopsis. Journal of Comparative Physiology B Biochemical Systemic & Environmental Physiology 154(3): 257-268

Single, giant and smooth muscle cells were isolated enzymatically from longitudinal muscle bundles in the ctenophore Mnemiopsis. The isolation procedure produced fragments of in situ cells and their lengths ranged from 100 .mu.m to several millimeters. The cut ends of the fibers resealed readily and the input impedances of the isolated cells remained high. Intracellular recordings were obtained from in situ fibers and used as a baseline to compare with data from isolated cells. In situ fibers had negative resting potentials (-60 mV) and produced fast overshooting action potentials when depolarized. The resting potentials and action potential parameters of the isolated cells were essentially similar. Isolated cells were very permeable to Cl- ions but in Cl--free media the resting potential was K+ dependent. The action potential in the isolated cell could be partially blocked by D-600 [methoxyverapamil], verapamil and Cd2+, implying that there is a Ca2+ component to the spike. Spike amplitude was decreased when external Na+ was reduced, suggesting that there is also a Na+ dependency. Repolarization was achieved by a tetraethylammonium and 4-aminopyridine [4-AP]-sensitive, K+ efflux, part of which passed through Ca+-activated channels. The 4-AP sensitive component gave rise to an after-depolarization that may have arisen because of extracellular accumulation of K+. Each action potential was associated with a discrete contraction from the fiber and when spike duration was increased, the twitches became very obvious.


Accession: 006670289

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Related references

Stein P.G.; Anderson P.A.V., 1984: The physiology of single giant smooth muscle cells isolated from the ctenophore mnemiopsis. Biophysical Journal 45(2 PART 2): 233A

Stein, P.G.; Anderson, P.A., 1984: Maintenance of isolated smooth muscle cells of the ctenophore Mnemiopsis. Journal of Experimental Biology 110: 329-334

Dubas, F.; Stein, P.G.; Anderson, P.A., 1988: Ionic currents of smooth muscle cells isolated from the ctenophore Mnemiopsis. The ionic currents of smooth muscle cells isolated from the ctenophore Mnemiopsis were examined by using conventional two-electrode voltage clamp and whole-cell patch clamping methods. Several separable currents were identified. These include: (1)...

Hernandez Nicaise M L.; Nicaise G.; Malaval L., 1984: Giant smooth muscle fibers of the ctenophore mnemiopsis leydii ultrastructural study of in situ and isolated cells. The lobate ctenophore M. leydii possesses giant smooth muscle fibers grouped in 2 sagittal bundles. Functional isolated cells were obtained by an enzymatic digestion of mesoglea and epithelia. Each bundle is made of 30-50 multinucleated cylindrica...

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