[Effects of isovitexin on transient outward potassium current of ventricular myocytes in rats].
Zhongguo Zhong Yao Za Zhi
; 42(24): 4864-4869, 2017 Dec.
Article
en Zh
| MEDLINE
| ID: mdl-29493159
ABSTRACT
To investigate the effects of isovitexin â
£ on transient outward potassium current in rat ventricular myocytes. In this study, MTT assay was used to investigate the safe range of isovitexin. The results showed that the IC50 of the drug was in the range of 10-30 µmolâ¢L⻹, and the drug concentration of 1-3 µmolâ¢L⻹ for the patch clamp test was within the safe range. In addition, the single ventricular myocytes were obtained by single-enzymatic hydrolysis through aortic retrograde perfusion. The transient outward potassium current (Ito) of rat ventricular myocytes was guided and measured by whole-cell patch-clamp technique and the changes of current characteristics were recorded after isovite was applied. When the concentration of IV was less than 0.1 µmolâ¢L⻹, there was no significant effect on Ito. However, with the increase in the concentration of IV (≥0.3 µmolâ¢L⻹), the peak of Ito was decreased gradually, from (32.32±2.9) pA/pF to ï¼25.83±4.3ï¼ pA/pF, 1 µmolâ¢L⻹ IV and (19.51±3.5) pA/pF, 3 µmolâ¢L⻹ IV respectively, with an inhibition effect in a concentration-dependent manner. In the range of 1-3 µmolâ¢L⻹, IV down-regulated the I-V curve of Ito significantly. The activation curve showed that IV can enable the maximum half activation potential (V1/2) to move to the positive direction, and the V1/2 was increased from (19.59±1.6) mV to (22.81±1.7) mV and (28.86±1.4) mV at concentration of 1, 3 µmolâ¢L⻹, meanwhile the activation curve moved to the right. However, the maximum half inactivating potential (V1/2) of the steady-state inactivation curve of Ito was significantly decreased from (ï¼51.43±0.99) mV to (ï¼61.81±1.3) mV with concentration of 1 µmolâ¢L⻹ and (ï¼71.50±1.4) mV with concentration of 3 µmolâ¢L⻹. The inactivation time constant of recovery from inactivation (τ) was up-regulated significantly from (94.89±0.73) ms to (118.5±1.5) ms and (162.4±1.4) ms at concentration of 1, 3 µmolâ¢L⻹ respectively. Meanwhile IV could enable the inactivation recovery curve to move to the right, which suggested that it can prolong the recovery time from inactivation of the transient outward potassium channel. In conclusion, isovitexin had a high inhibitory effect on Ito in rat ventricular myocytes.
Palabras clave
Texto completo:
1
Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Canales de Potasio
/
Miocitos Cardíacos
/
Apigenina
/
Canales de Potencial de Receptor Transitorio
Límite:
Animals
Idioma:
Zh
Revista:
Zhongguo Zhong Yao Za Zhi
Asunto de la revista:
FARMACOLOGIA
/
TERAPIAS COMPLEMENTARES
Año:
2017
Tipo del documento:
Article
País de afiliación:
China