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Effects of halothane on action potential configuration in sub-endocardial and sub-epicardial myocytes from normotensive and hypertensive rat left ventricle.
Br J Anaesth. 2003 Apr; 90(4):501-3.BJ

Abstract

BACKGROUND

Halothane shortens ventricular action potential duration (APD), as a consequence of its inhibitory effects on a variety of membrane currents, an effect that is greater in sub-endocardial than sub-epicardial myocytes. In hypertrophied ventricle, APD is prolonged as a consequence of electrical remodelling. In this study, we compared the effects of halothane on transmural APD in myocytes from normal and hypertrophied ventricle.

METHODS

Myocytes were isolated from the sub-endocardium and sub-epicardium of the left ventricle of spontaneously hypertensive (SHR) and normotensive Wistar-Kyoto (WKY) rats. Action potentials were recorded before, during, and after a 1-min exposure to 0.6 mM halothane and APD measured from the peak of the action potential to repolarization at -50 mV (APD(-50 mV)). Data are presented as mean (SEM).

RESULTS

In WKY myocytes, halothane reduced APD(-50 mV) from 21 (2) to 18 (2) ms (P<0.001, n=15) in sub-epicardial myocytes but abbreviated APD(-50 mV) to a greater extent in sub-endocardial myocytes (37 (4) to 28 (3) ms; P<0.001, n=14). In SHR myocytes, APD(-50 mV) values were prolonged compared with WKY and APD(-50 mV) was reduced by halothane from 36 (6) to 27 (4) ms (P<0.016) and from 77 (10) to 38 (4) ms (P<0.001) in sub-epicardial and sub-endocardial myocytes, respectively.

CONCLUSIONS

In the SHR, hypertrophic remodelling was not homogeneous; APD(-50 mV) was prolonged to a greater extent in sub-endocardial than sub-epicardial cells. Halothane reduced APD to a greater extent in sub-endocardium than sub-epicardium in both WKY and SHR but this effect was larger proportionately in SHR myocytes. The transmural gradient of repolarization was reduced in WKY and effectively abolished in SHR by halothane, which might disturb normal ventricular repolarization.

Authors+Show Affiliations

Rithalia A
School of Biomedical Sciences and Academic Unit of Anaesthesia, University of Leeds, Leeds LS2 9JT, UK.
Hopkins PM
No affiliation info available
Harrison SM
No affiliation info available

MeSH

Action PotentialsAnesthetics, InhalationAnimalsEndocardiumHalothaneHypertensionHypertrophy, Left VentricularMyocytes, CardiacPericardiumRatsRats, Inbred SHRRats, Inbred WKYVentricular Remodeling

Pub Type(s)

Journal Article

Language

eng

PubMed ID

12644424

Citation

Rithalia, A, et al. "Effects of Halothane On Action Potential Configuration in Sub-endocardial and Sub-epicardial Myocytes From Normotensive and Hypertensive Rat Left Ventricle." British Journal of Anaesthesia, vol. 90, no. 4, 2003, pp. 501-3.
Rithalia A, Hopkins PM, Harrison SM. Effects of halothane on action potential configuration in sub-endocardial and sub-epicardial myocytes from normotensive and hypertensive rat left ventricle. Br J Anaesth. 2003;90(4):501-3.
Rithalia, A., Hopkins, P. M., & Harrison, S. M. (2003). Effects of halothane on action potential configuration in sub-endocardial and sub-epicardial myocytes from normotensive and hypertensive rat left ventricle. British Journal of Anaesthesia, 90(4), 501-3.
Rithalia A, Hopkins PM, Harrison SM. Effects of Halothane On Action Potential Configuration in Sub-endocardial and Sub-epicardial Myocytes From Normotensive and Hypertensive Rat Left Ventricle. Br J Anaesth. 2003;90(4):501-3. PubMed PMID: 12644424.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Effects of halothane on action potential configuration in sub-endocardial and sub-epicardial myocytes from normotensive and hypertensive rat left ventricle. AU - Rithalia,A, AU - Hopkins,P M, AU - Harrison,S M, PY - 2003/3/20/pubmed PY - 2003/5/9/medline PY - 2003/3/20/entrez SP - 501 EP - 3 JF - British journal of anaesthesia JO - Br J Anaesth VL - 90 IS - 4 N2 - BACKGROUND: Halothane shortens ventricular action potential duration (APD), as a consequence of its inhibitory effects on a variety of membrane currents, an effect that is greater in sub-endocardial than sub-epicardial myocytes. In hypertrophied ventricle, APD is prolonged as a consequence of electrical remodelling. In this study, we compared the effects of halothane on transmural APD in myocytes from normal and hypertrophied ventricle. METHODS: Myocytes were isolated from the sub-endocardium and sub-epicardium of the left ventricle of spontaneously hypertensive (SHR) and normotensive Wistar-Kyoto (WKY) rats. Action potentials were recorded before, during, and after a 1-min exposure to 0.6 mM halothane and APD measured from the peak of the action potential to repolarization at -50 mV (APD(-50 mV)). Data are presented as mean (SEM). RESULTS: In WKY myocytes, halothane reduced APD(-50 mV) from 21 (2) to 18 (2) ms (P<0.001, n=15) in sub-epicardial myocytes but abbreviated APD(-50 mV) to a greater extent in sub-endocardial myocytes (37 (4) to 28 (3) ms; P<0.001, n=14). In SHR myocytes, APD(-50 mV) values were prolonged compared with WKY and APD(-50 mV) was reduced by halothane from 36 (6) to 27 (4) ms (P<0.016) and from 77 (10) to 38 (4) ms (P<0.001) in sub-epicardial and sub-endocardial myocytes, respectively. CONCLUSIONS: In the SHR, hypertrophic remodelling was not homogeneous; APD(-50 mV) was prolonged to a greater extent in sub-endocardial than sub-epicardial cells. Halothane reduced APD to a greater extent in sub-endocardium than sub-epicardium in both WKY and SHR but this effect was larger proportionately in SHR myocytes. The transmural gradient of repolarization was reduced in WKY and effectively abolished in SHR by halothane, which might disturb normal ventricular repolarization. SN - 0007-0912 UR - https://www.unboundmedicine.com/medline/citation/12644424/Effects_of_halothane_on_action_potential_configuration_in_sub_endocardial_and_sub_epicardial_myocytes_from_normotensive_and_hypertensive_rat_left_ventricle_ DB - PRIME DP - Unbound Medicine ER -