Comparison of spontaneous and noradrenaline-evoked non-selective cation channels in rabbit portal vein myocytes

Albert, A. P. ORCID: https://orcid.org/0000-0002-3596-9634 and Large, W. A. (2001) Comparison of spontaneous and noradrenaline-evoked non-selective cation channels in rabbit portal vein myocytes. Journal of Physiology, 530 (3). pp. 457-468. ISSN 0022-3751

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Abstract

1. The properties of non-selective cation channels were studied in rabbit portal vein smooth muscle cells in K+-free conditions with patch pipette techniques. 2. In about 45% of isolated-out patches spontaneous channel currents with a unitary conductance of 23 pS were observed. The reversal potential was +11 mV, which was shifted to more negative values and the unitary conductance was reduced when part of the external Na+ was replaced by Tris. 3. At negative potentials the probability of opening (Po) was low and the open time distributions were described by two exponentials with time constants of about 1 and 7 ms. At positive potentials Po and the longer mean open time were greatly increased. 4. The channel exhibited bursting behaviour and the burst duration distributions were described by two exponentials with time constants of about 3 and 15 ms. At positive potentials the longer burst duration was increased substantially. 5. Application of noradrenaline and the diacylglycerol analogue 1-oleoyl-2-acetyl-sn-glycerol (OAG) to the external membrane of quiescent patches evoked single-channel activity with a unitary conductance of about 23 pS and with similar kinetic behaviour to that of the spontaneous channel currents. 6. In conclusion, noradrenaline and OAG activate non-selective cation channel currents in excised patches of rabbit portal vein myocytes with a unitary conductance and kinetic properties that are similar to those of spontaneous channel currents. These channels have two open states and exhibit bursting behaviour. It is suggested that these channels underlie the whole-cell currents evoked by noradrenaline and OAG.

Item Type: Article
Uncontrolled Keywords: physiology ,/dk/atira/pure/subjectarea/asjc/1300/1314
Faculty \ School: Faculty of Medicine and Health Sciences > Norwich Medical School
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Depositing User: LivePure Connector
Date Deposited: 29 Oct 2024 09:30
Last Modified: 03 Nov 2024 07:31
URI: https://ueaeprints.uea.ac.uk/id/eprint/97284
DOI: 10.1111/j.1469-7793.2001.0457k.x

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