Stimulation of single isolated adult ventricular myocytes within a low volume using a planar microelectrode array.
Microchannels (40- microm wide, 10- microm high, 10-mm long, 70- microm pitch) were patterned in the silicone elastomer, polydimethylsiloxane on a microscope coverslip base. Integrated within each microchamber were individually addressable stimulation electrodes (40- microm wide, 20- microm long, 100-nm thick) and a common central pseudo-reference electrode (60- microm wide, 500- microm long, 100-nm thick). Isolated rabbit ventricular myocytes were introduced into the chamber by micropipetting and subsequently capped with a layer of mineral oil, thus creating limited volumes of saline around individual myocytes that could be varied from 5 nL to 100 pL. Excitation contraction coupling was studied by monitoring myocyte shortening and intracellular Ca(2+) transients (using Fluo-3 fluorescence). The amplitude of stimulated myocyte shortening and Ca(2+) transients remained constant for 90 min in the larger volume (5 nL) configuration, although the shortening (but not the Ca(2+) transient) amplitude gradually decreased to 20% of control within 60 min in the low volume (100 pL) arrangement. These studies indicate a lower limit for the extracellular volume required to stimulate isolated adult cardiac myocytes. Whereas this arrangement could be used to create a screening assay for drugs, individual microchannels (100 pL) can also be used to study the effects of limited extracellular volume on the contractility of single cardiac myocytes.
Klauke
Norbert
N
Department of Electronics, University of Glasgow, Glasgow, United Kingdom. norbert@elec.gla.ac.uk
Smith
Godfrey L
GL
Cooper
Jon
J
D000818:Animals; D002118:Calcium / Q000737:chemistry / Q000378:metabolism; D004129:Dimethylpolysiloxanes / Q000737:chemistry*; D004566:Electrodes; D004594:Electrophysiology; D006352:Heart Ventricles / Q000166:cytology; D006801:Humans; D018613:Microscopy, Confocal; D008899:Mineral Oil; D009206:Myocardium / Q000378:metabolism; D032383:Myocytes, Cardiac / Q000378:metabolism*; D011817:Rabbits; D012828:Silicones / Q000737:chemistry*
D004129:Dimethylpolysiloxanes; D012828:Silicones; C013830:baysilon; D008899:Mineral Oil; D002118:Calcium