Investigating the Effect of Serotonin II and III Receptor Inhibitors on the Chronotropic Changes of the Heart to Isoproterenol in Rat Models of Biliary Cirrhosis

Abstract

Cirrhotic patients have hyperdynamic circulation and at-rest tachycardia, and agents that activate the sympathetic pathway, such as physical practice and pharmacologic stimulations, compared with the normal population, cannot cause enough increase in heartbeat, a condition known as cirrhotic cardiomyopathy. Concerning the presentation of 5-HT2 & 5-HT3 receptors in rat hearts, we used Ketanserin as a 5-HT2 receptor inhibitor & Tropisetron as a 5-HT3 receptor inhibitor to evaluate chronic therapeutic effects of 5-HT2 & 5-HT3 antagonists on the cardiac chronotropic response of cirrhotic rats to adrenergics. Cirrhosis was induced by surgical ligation of the bile duct in Male Wistar rats, and another group remained sham. A week after bile duct ligation or sham surgery, the subjects were given an intraperitoneal injection of either saline or Tropisetron (2 mg/kg). In other BDL & Sharm groups, the subjects were given an intraperitoneal injection of either saline or Ketanserin (6 mg/kg) every other 3 days in the last 3 weeks. Four weeks after bile duct ligation or sham surgery, the atria were isolated and chronotropic responsiveness to Isoproterenol was assessed using a standard organ bath. Our data showed that chronic treatment with Tropisetron (5-HT3 antagonist) in cirrhotic rats could decrease the cardiac chronotropic response. Chronic treatment with Tropisetron can cause a significant decrease in cardiac chronotropic response to Isoproterenol in healthy and cirrhotic rats, even lower than that in cirrhotic rats (without any special treatment). Chronic treatment with Ketanserin cannot change their impaired chronotropic response to Isoproterenol.