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Apico-basal inhomogeneity in distribution of ion channels in canine and human ventricular myocardium.
Cardiovasc Res. 2005 Mar 01; 65(4):851-60.CR

Abstract

OBJECTIVES

The aim of the present study was to compare the apico-basal distribution of ion currents and the underlying ion channel proteins in canine and human ventricular myocardium.

METHODS

Ion currents and action potentials were recorded in canine cardiomyocytes, isolated from both apical and basal regions of the heart, using whole-cell voltage clamp techniques. Density of channel proteins in canine and human ventricular myocardium was determined by Western blotting.

RESULTS

Action potential duration was shorter and the magnitude of phase-1 repolarization was significantly higher in apical than basal canine myocytes. No differences were observed in other parameters of the action potential or cell capacitance. Amplitude of the transient outward K(+) current (29.6+/-5.7 versus 16.5+/-4.4 pA/pF at +65 mV) and the slow component of the delayed rectifier K(+) current (5.61+/-0.43 versus 2.14+/-0.18 pA/pF at +50 mV) were significantly larger in apical than in basal myocytes. Densities of the inward rectifier K(+) current, rapid delayed rectifier K(+) current, and L-type Ca(2+) current were similar in myocytes of apical and basal origin. Apico-basal differences were found in the expression of only those channel proteins which are involved in mediation of the transient outward K(+) current and the slow delayed rectifier K(+) current: expression of Kv1.4, KChIP2, KvLQT1 and MinK was significantly higher in apical than in basal myocardium in both canine and human hearts.

CONCLUSIONS

The results suggest that marked apico-basal electrical inhomogeneity exists in the canine-and probably in the human-ventricular myocardium, which may result in increased dispersion, and therefore, cannot be ignored when interpreting ECG recordings, pathological alterations, or drug effects.

Authors+Show Affiliations

Department of Physiology, University of Debrecen, P.O. Box 22, H-4012 Debrecen, Hungary.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

15721865

Citation

Szentadrassy, Norbert, et al. "Apico-basal Inhomogeneity in Distribution of Ion Channels in Canine and Human Ventricular Myocardium." Cardiovascular Research, vol. 65, no. 4, 2005, pp. 851-60.
Szentadrassy N, Banyasz T, Biro T, et al. Apico-basal inhomogeneity in distribution of ion channels in canine and human ventricular myocardium. Cardiovasc Res. 2005;65(4):851-60.
Szentadrassy, N., Banyasz, T., Biro, T., Szabo, G., Toth, B. I., Magyar, J., Lazar, J., Varro, A., Kovacs, L., & Nanasi, P. P. (2005). Apico-basal inhomogeneity in distribution of ion channels in canine and human ventricular myocardium. Cardiovascular Research, 65(4), 851-60.
Szentadrassy N, et al. Apico-basal Inhomogeneity in Distribution of Ion Channels in Canine and Human Ventricular Myocardium. Cardiovasc Res. 2005 Mar 1;65(4):851-60. PubMed PMID: 15721865.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Apico-basal inhomogeneity in distribution of ion channels in canine and human ventricular myocardium. AU - Szentadrassy,Norbert, AU - Banyasz,Tamas, AU - Biro,Tamas, AU - Szabo,Gergely, AU - Toth,Balazs I, AU - Magyar,Janos, AU - Lazar,Jozsef, AU - Varro,Andras, AU - Kovacs,Laszlo, AU - Nanasi,Peter P, PY - 2004/06/24/received PY - 2004/11/17/revised PY - 2004/11/18/accepted PY - 2005/2/22/pubmed PY - 2005/4/20/medline PY - 2005/2/22/entrez SP - 851 EP - 60 JF - Cardiovascular research JO - Cardiovasc Res VL - 65 IS - 4 N2 - OBJECTIVES: The aim of the present study was to compare the apico-basal distribution of ion currents and the underlying ion channel proteins in canine and human ventricular myocardium. METHODS: Ion currents and action potentials were recorded in canine cardiomyocytes, isolated from both apical and basal regions of the heart, using whole-cell voltage clamp techniques. Density of channel proteins in canine and human ventricular myocardium was determined by Western blotting. RESULTS: Action potential duration was shorter and the magnitude of phase-1 repolarization was significantly higher in apical than basal canine myocytes. No differences were observed in other parameters of the action potential or cell capacitance. Amplitude of the transient outward K(+) current (29.6+/-5.7 versus 16.5+/-4.4 pA/pF at +65 mV) and the slow component of the delayed rectifier K(+) current (5.61+/-0.43 versus 2.14+/-0.18 pA/pF at +50 mV) were significantly larger in apical than in basal myocytes. Densities of the inward rectifier K(+) current, rapid delayed rectifier K(+) current, and L-type Ca(2+) current were similar in myocytes of apical and basal origin. Apico-basal differences were found in the expression of only those channel proteins which are involved in mediation of the transient outward K(+) current and the slow delayed rectifier K(+) current: expression of Kv1.4, KChIP2, KvLQT1 and MinK was significantly higher in apical than in basal myocardium in both canine and human hearts. CONCLUSIONS: The results suggest that marked apico-basal electrical inhomogeneity exists in the canine-and probably in the human-ventricular myocardium, which may result in increased dispersion, and therefore, cannot be ignored when interpreting ECG recordings, pathological alterations, or drug effects. SN - 0008-6363 UR - https://www.unboundmedicine.com/medline/citation/15721865/Apico_basal_inhomogeneity_in_distribution_of_ion_channels_in_canine_and_human_ventricular_myocardium_ L2 - https://academic.oup.com/cardiovascres/article-lookup/doi/10.1016/j.cardiores.2004.11.022 DB - PRIME DP - Unbound Medicine ER -