Steroids have been known to exert a number of pharmacological actions aside from its hormonal activities. Included are anesthetic, hemolytic, hemopoietic, hypocholesterolemic, antibacterial and antihypertensive activities.
Bile acids, a derivatives of cholesterol, possess many of aforementioned proper-ties of steriods. It has been reported that intravenous administration of bile acids results in bradycardia and hypotension and that bile acids, like digitails and sex steroids, can
x alter transmembrane potentials of cardiac cells.
The present study was undertaken to explore arrhythmogenic and antiarrhythmic effect of bile acids and the results obtained were as follows;
k 1. No singnificant changes were observed in the action potential amplitude and rate of spontaneous firing of the sinoatrial node cell following superfusion with
_ taurocholate (TCA, 0.05%).
2. The spontaneous arrhythmias were abolished by TCA in approximately 85% of experimental cases.
3. Arrhythmias were produced in approximately 30% of experimental cases following superfusion of sinus node cells with cholate (CA, 0.05%), glycocholate (GCA, 0.05%), and deoxycholate (DCA, 0.0250%) solutions, respectively.
4. When the sinoatrial node cells were superfused with TCA for 5 min, CA-induced arrhythmias were abolished in 8.0+1.5 min, on average.
5. TCA abolished GCA-and DCA-induced arrhythimas in 17.0 5.7 min, and 19.5 1.2 min, respectively.
The results of present study indicate that some bile acids. are arrhythmogenic while others antiarrhythmic.
|