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L-type calcium current in right ventricular outflow tract myocytes of rabbit heart.
Sci China Life Sci. 2012 Jan; 55(1):41-6.SC

Abstract

The mechanism of idiopathic ventricular tachycardia originating from the right ventricular outflow tract (RVOT) is not clear. Many clinical reports have suggested a mechanism of triggered activity. However, there are few studies investigating this because of the technical difficulties associated with examining this theory. The L-type calcium current (I (Ca-L)), an important inward current of the action potential (AP), plays an important role in arrhythmogenesis. The aim of this study was to explore differences in the APs of right ventricular (RV) and RVOT cardiomyocytes, and differences in electrophysiological characteristics of the ICa-L in these myocytes. Rabbit RVOT and RV myocytes were isolated and their AP and I (Ca-L) were investigated using the patch-clamp technique. RVOT cardiomyocytes had a wider range of AP duration (APD) than RV cardiomyocytes, with some markedly prolonged APDs and markedly shortened APDs. The markedly shortened APDs in RVOT myocytes were abolished by treatment with 4-AP, an inhibitor of the transient outward potassium current, but the markedly prolonged APDs remained, with some myocytes with a long AP plateau not repolarizing to resting potential. In addition, early afterdepolarization (EAD) and second plateau responses were seen in RVOT myocytes but not in RV myocytes. RVOT myocytes had a higher current density for I (Ca-L) than RV myocytes (RVOT (13.16±0.87) pA pF(-1), RV (8.59±1.97) pA pF(-1); P<0.05). The I (Ca-L) and the prolonged APD were reduced, and the EAD and second plateau response disappeared, after treatment with nifedipine (10 μmol L(-1)), which blocks the I (Ca-L). In conclusion, there was a wider range of APDs in RVOT myocytes than in RV myocytes, which is one of the basic factors involved in arrhythmogenesis. The higher current density for I (Ca-L) is one of the factors causing prolongation of the APD in RVOT myocytes. The combination of EAD with prolonged APD may be one of the mechanisms of RVOT-VT generation.

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Publisher Full Text (DOI)

Authors+Show Affiliations

Liang S
Fujian Medical University Graduate Student Education Institute, Fuzhou 350004, China.
Lin C
No affiliation info available
Li Y
No affiliation info available
Liu T
No affiliation info available
Wang Y
No affiliation info available

MeSH

Action PotentialsAnimalsCalcium Channels, L-TypeHeart VentriclesHumansMaleMyocytes, CardiacPatch-Clamp TechniquesRabbitsTachycardia, Ventricular

Pub Type(s)

Journal Article

Language

eng

PubMed ID

22314490

Citation

Liang, Shenghui, et al. "L-type Calcium Current in Right Ventricular Outflow Tract Myocytes of Rabbit Heart." Science China. Life Sciences, vol. 55, no. 1, 2012, pp. 41-6.
Liang S, Lin C, Li Y, et al. L-type calcium current in right ventricular outflow tract myocytes of rabbit heart. Sci China Life Sci. 2012;55(1):41-6.
Liang, S., Lin, C., Li, Y., Liu, T., & Wang, Y. (2012). L-type calcium current in right ventricular outflow tract myocytes of rabbit heart. Science China. Life Sciences, 55(1), 41-6. https://doi.org/10.1007/s11427-012-4265-3
Liang S, et al. L-type Calcium Current in Right Ventricular Outflow Tract Myocytes of Rabbit Heart. Sci China Life Sci. 2012;55(1):41-6. PubMed PMID: 22314490.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - L-type calcium current in right ventricular outflow tract myocytes of rabbit heart. AU - Liang,Shenghui, AU - Lin,Chenhui, AU - Li,Yuan, AU - Liu,Taifeng, AU - Wang,Yan, Y1 - 2012/02/08/ PY - 2011/09/28/received PY - 2011/11/10/accepted PY - 2012/2/9/entrez PY - 2012/2/9/pubmed PY - 2012/5/23/medline SP - 41 EP - 6 JF - Science China. Life sciences JO - Sci China Life Sci VL - 55 IS - 1 N2 - The mechanism of idiopathic ventricular tachycardia originating from the right ventricular outflow tract (RVOT) is not clear. Many clinical reports have suggested a mechanism of triggered activity. However, there are few studies investigating this because of the technical difficulties associated with examining this theory. The L-type calcium current (I (Ca-L)), an important inward current of the action potential (AP), plays an important role in arrhythmogenesis. The aim of this study was to explore differences in the APs of right ventricular (RV) and RVOT cardiomyocytes, and differences in electrophysiological characteristics of the ICa-L in these myocytes. Rabbit RVOT and RV myocytes were isolated and their AP and I (Ca-L) were investigated using the patch-clamp technique. RVOT cardiomyocytes had a wider range of AP duration (APD) than RV cardiomyocytes, with some markedly prolonged APDs and markedly shortened APDs. The markedly shortened APDs in RVOT myocytes were abolished by treatment with 4-AP, an inhibitor of the transient outward potassium current, but the markedly prolonged APDs remained, with some myocytes with a long AP plateau not repolarizing to resting potential. In addition, early afterdepolarization (EAD) and second plateau responses were seen in RVOT myocytes but not in RV myocytes. RVOT myocytes had a higher current density for I (Ca-L) than RV myocytes (RVOT (13.16±0.87) pA pF(-1), RV (8.59±1.97) pA pF(-1); P<0.05). The I (Ca-L) and the prolonged APD were reduced, and the EAD and second plateau response disappeared, after treatment with nifedipine (10 μmol L(-1)), which blocks the I (Ca-L). In conclusion, there was a wider range of APDs in RVOT myocytes than in RV myocytes, which is one of the basic factors involved in arrhythmogenesis. The higher current density for I (Ca-L) is one of the factors causing prolongation of the APD in RVOT myocytes. The combination of EAD with prolonged APD may be one of the mechanisms of RVOT-VT generation. SN - 1869-1889 UR - https://www.unboundmedicine.com/medline/citation/22314490/L_type_calcium_current_in_right_ventricular_outflow_tract_myocytes_of_rabbit_heart_ L2 - https://dx.doi.org/10.1007/s11427-012-4265-3 DB - PRIME DP - Unbound Medicine ER -