Genistein inhibits carotid sinus baroreceptor activity in anesthetized male rats.

AIM

To study the effect of genistein (GST) on carotid baroreceptor activity (CBA).

METHODS

The functional curve of carotid baroreceptor (FCCB) was constructed and the functional parameters of carotid baroreceptor were measured by recording sinus nerve afferent discharge in anesthetized male rats with perfused isolated carotid sinus.

RESULTS

GST at 50, 100, and 200 micromol/L inhibited the CBA, which shifted FCCB to the right and downward, with a marked decrease in peak slope and peak integral value of carotid sinus nerve discharge in a concentration-dependent manner. Pretreatment with 100 micromol/L NG-nitro-L-arginine methyl ester, an inhibitor of nitric oxide synthase, did not affect the effect of GST on CBA. Pretreatment with 500 nmol/L Bay K8644, an agonist of calcium channels, could completely abolish the effect of GST on CBA. A potent inhibitor of tyrosine phosphatase, sodium orthovanadate (1 mmol/L), could attenuate the inhibitory effect of GST.

CONCLUSION

GST inhibits CBA, and the effect may be mediated by protein tyrosine kinase inhibition and a decrease in Ca2+ influx through the stretch-activated channels.