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Effect of agmatine on L-type calcium current in rat ventricular myocytes.
Acta Pharmacol Sin. 2002 Mar; 23(3):219-24.AP

Abstract

AIM

To study the effect of agmatine (Agm) on L-type calcium current (I(Ca-L)) in rat ventricular myocytes.

METHODS

Whole-cell configuration of the patch-clamp technique was used to record I(Ca-L) in single rat ventricular myocytes which were dissociated by enzymatic dissociation method.

RESULTS

(1) Agm (0.5, 1, 2 mmol/L) reduced the voltage-dependently activated peak amplitude of I(Ca-L) (pA) from 1451+/-236 (control) to 937+/-105 (n=8, P <0.05), 585+/-74 (n=8, P <0.01), and to 301+/-156 (n=8, P <0.01) in a concentration-dependent manner. (2) Agm (1 mmol/L) blocked I(Ca-L) in a use-dependent manner. The degree of use-dependent blocking effect was 53 %+/-12 % (n=8, P <0.05) at 1 Hz, and 69 %+/-11 % (n=8, P <0.01) at 3 Hz. (3) Agm upshifted the current-voltage (I-V) curve, but the characteristics of I-V relationship were not significantly altered by Agm, the maximal activation voltage of I(Ca-L) was not different from that of control. Steady-state activation of I(Ca-L) was not affected markedly. The half activation potential (V(0.5)) and the slope factor (k) were not significantly different from those of the control. V(0.5) value was (-20.2+/-2.5) mV in the control and (-20.5+/-2.7) mV in the presence of Agm 1 mmol/L. The k value was (7.1+/-0.4) mV and (7.5+/-0.5) mV, respectively (n=8, P >0.05). (4) Agm 1 mmol/L markedly shifted the steady-state inactivation curve of I(Ca-L) to the left, and accelerated the voltage-dependent steady-state inactivation of calcium current. V(0.5) value was (-32+/-6) mV in the control and (-40+/-5) mV in the presence of Agm. The k value was (7.6+/-0.9) mV and (12.5+/-1.1) mV, respectively (n=8, P <0.05). (5) Agm 1 mmol/L markedly delayed half-recovery time of Ca2+ channel from inactivation (92+/-28) ms to (249+/-26) ms (n=8, P <0.01).

CONCLUSION

Agm inhibited I(Ca-L) and mainly acted on the inactivated state of L-type calcium channel, manifested as acceleration of calcium channel inactivation and slowdown of recovery from inactivated state in rat ventricular myocytes.

Authors+Show Affiliations

Li Q
Department of Physiology, Institute of Basic Medicine, Hebei Medical University, Shijiazhuang 050017, China.
Yin JX
No affiliation info available
He RR
No affiliation info available

MeSH

AgmatineAnimalsCalcium Channel BlockersCalcium Channels, L-TypeCell SeparationHeart VentriclesMicroelectrodesMuscle CellsPatch-Clamp TechniquesRats

Pub Type(s)

Journal Article

Language

eng

PubMed ID

11918845

Citation

Li, Qing, et al. "Effect of Agmatine On L-type Calcium Current in Rat Ventricular Myocytes." Acta Pharmacologica Sinica, vol. 23, no. 3, 2002, pp. 219-24.
Li Q, Yin JX, He RR. Effect of agmatine on L-type calcium current in rat ventricular myocytes. Acta Pharmacol Sin. 2002;23(3):219-24.
Li, Q., Yin, J. X., & He, R. R. (2002). Effect of agmatine on L-type calcium current in rat ventricular myocytes. Acta Pharmacologica Sinica, 23(3), 219-24.
Li Q, Yin JX, He RR. Effect of Agmatine On L-type Calcium Current in Rat Ventricular Myocytes. Acta Pharmacol Sin. 2002;23(3):219-24. PubMed PMID: 11918845.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Effect of agmatine on L-type calcium current in rat ventricular myocytes. AU - Li,Qing, AU - Yin,Jing-Xiang, AU - He,Rui-Rong, PY - 2002/3/29/pubmed PY - 2003/9/17/medline PY - 2002/3/29/entrez SP - 219 EP - 24 JF - Acta pharmacologica Sinica JO - Acta Pharmacol Sin VL - 23 IS - 3 N2 - AIM: To study the effect of agmatine (Agm) on L-type calcium current (I(Ca-L)) in rat ventricular myocytes. METHODS: Whole-cell configuration of the patch-clamp technique was used to record I(Ca-L) in single rat ventricular myocytes which were dissociated by enzymatic dissociation method. RESULTS: (1) Agm (0.5, 1, 2 mmol/L) reduced the voltage-dependently activated peak amplitude of I(Ca-L) (pA) from 1451+/-236 (control) to 937+/-105 (n=8, P <0.05), 585+/-74 (n=8, P <0.01), and to 301+/-156 (n=8, P <0.01) in a concentration-dependent manner. (2) Agm (1 mmol/L) blocked I(Ca-L) in a use-dependent manner. The degree of use-dependent blocking effect was 53 %+/-12 % (n=8, P <0.05) at 1 Hz, and 69 %+/-11 % (n=8, P <0.01) at 3 Hz. (3) Agm upshifted the current-voltage (I-V) curve, but the characteristics of I-V relationship were not significantly altered by Agm, the maximal activation voltage of I(Ca-L) was not different from that of control. Steady-state activation of I(Ca-L) was not affected markedly. The half activation potential (V(0.5)) and the slope factor (k) were not significantly different from those of the control. V(0.5) value was (-20.2+/-2.5) mV in the control and (-20.5+/-2.7) mV in the presence of Agm 1 mmol/L. The k value was (7.1+/-0.4) mV and (7.5+/-0.5) mV, respectively (n=8, P >0.05). (4) Agm 1 mmol/L markedly shifted the steady-state inactivation curve of I(Ca-L) to the left, and accelerated the voltage-dependent steady-state inactivation of calcium current. V(0.5) value was (-32+/-6) mV in the control and (-40+/-5) mV in the presence of Agm. The k value was (7.6+/-0.9) mV and (12.5+/-1.1) mV, respectively (n=8, P <0.05). (5) Agm 1 mmol/L markedly delayed half-recovery time of Ca2+ channel from inactivation (92+/-28) ms to (249+/-26) ms (n=8, P <0.01). CONCLUSION: Agm inhibited I(Ca-L) and mainly acted on the inactivated state of L-type calcium channel, manifested as acceleration of calcium channel inactivation and slowdown of recovery from inactivated state in rat ventricular myocytes. SN - 1671-4083 UR - https://www.unboundmedicine.com/medline/citation/11918845/Effect_of_agmatine_on_L_type_calcium_current_in_rat_ventricular_myocytes_ DB - PRIME DP - Unbound Medicine ER -