Cellular pathways of the conducted electrical response in arterioles of hamster cheek pouch in vitro. Xia, J., T. L. Little, and B. R. Duling. Department of Molecular Physiology and Biological Physics School of Medicine, University of Virginia, Charlottesville, VA 22908
APStracts 2:0314H, 1995.
We have previously shown that conducted vasomotor responses follow patterns that are consistent with a passive spread of electrical current along the length of the arterioles (31). In this study, we define the cells through which the current flows. Arterioles of hamster cheek pouch were superfused with bicarbonate-buffered saline. KCl or phenylephrine (PE) were applied through glass pipettes placed close to the arterioles by pressure or current ejection, respectively. Cell membrane potentials were recorded using glass microelectrodes filled with either 2 M KCl or 0.1 M KCl + 1.3% dextran fluorescence for marking the injected cells. The mean resting membrane potential (RMP) for randomly sampled arteriolar cells was -67 +/- 0.7 mV, n = 30 (+/- SE). When cell types were identified by dye injection the RMPs were -68 +/- 1.4 mV (n = 21) and -67 +/- 1 mV (n = 12) for smooth muscle and endothelium, respectively. Brief pulses of KCl applied by pressure ejection induced transient, monophasic depolarizations at the site of stimulation (referred to here as "local"). These depolarizations were conducted decrementally along the length of the arteriole for several hundred micrometers. As the voltage changes spread along the vessel length, three patterns of electrical responses could be observed at the distant sites. Two of these were quite different from the local responses, but identical patterns of the conducted electrical response were observed in smooth muscle and endothelial cells. Stimulation with PE also caused transient local and conducted depolarizations in both smooth muscle and endothelial cells. As with KCl stimuli, shapes of conducted electrical responses were identical in records made in smooth muscle and endothelial cells. The results suggest that smooth muscle and endothelial cells are both homocellularly and heterocellularly electrically coupled, and that signals originating in smooth muscle cells can conduct through the endothelium. 

Received 19 January 1995; accepted in final form 11 July 1995.
APS Manuscript Number H52-5.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 30 July 1995.