Search

Aim: To compare the effects of AMP579 and adenosine on L-type Ca 2+ current ( I Ca-L ) in rat ventricular myocytes and explore the mechanism by which AMP579 acts on I Ca-L . Methods: I Ca-L was recorded by patch-clamp technique in whole-cell configuration. Results: Adenosine (10 nmol/L to 50 umol/L) showed no effect on basal I Ca-L , but it inhibited the I Ca-L induced by isoproterenol 10 nmol/L in a concentration-dependent manner with the IC 50 of 13.06 umol/L. Similar to adenosine, AMP579 also showed an inhibitory effect on the I Ca-L induced by isoproterenol. AMP579 and adenosine (both in 10 umol/L) suppressed isoproterenol-induced I Ca-L by 11.1% and 5.2%, respectively. In addition, AMP579 had a direct inhibitory effect on basal I Ca-L in a concentration-dependent manner with IC 50 (1.17 mumol/L). PD116948 (30 mumol/L), an adenosine A1 receptor blocker, showed no action on the inhibitory effect of AMP579 on basal I Ca-L . However, GF109203X (0.4 mumol/L), a special protein kinase C (PKC) blocker, could abolish the inhibitory effect of AMP579 on basal I Ca-L . So the inhibitory effect of AMP579 on basal ICa-L was induced through activating PKC, but not linked to adenosine A 1 receptor. Conclusion: AMP579 shows a stronger inhibitory effect than adenosine on the I Ca-L induced by isoproterenol. AMP579 also has a strong inhibitory effect on basal ICa-L in rat ventricular myocytes. Activation of PKC is involved in the inhibitory effect of AMP579 on basal I Ca-L at downstream-mechanism.

Aim: The aim of the present study was to investigate the effect of the antibody against alpha-2 repeat on Na + -Ca 2+ exchanger (NCX) current (I Na /Ca). To evaluate the functional specificity of this antibody, its effects on L-type Ca 2+ current (I Ca,L ), voltage-gated Na + current (I Na ) and delayed rectifier K+ current (I K ) were also observed. Methods: The whole-cell patch-clamp technique was used in this study. Results: The antibody against alpha-2 repeat augmented both the outward and inward Na + -Ca 2+ exchanger current concentration-dependently, with EC50 values of 27.9 nmol/L and 24.7 nmol/L, respectively. Meanwhile, the antibody could also increase I Ca,L in a concentration-dependent manner with the EC50 of 33.6 nmol/L. Effects of the antibody on I Na and I K were not observed in the present study. Conclusion: The present results suggest that antibody against alpha-2 repeat is a stimulating antibody to NCX and could also increase I Ca,L in a concentration-dependent manner, but did not have an obvious effect on I Na and I K .