The Effect of Ketamine on Heart Rate in an Isolated Atrial Preparation Taken From the Rat

Abstract

The effect of ketamine was tested on the heart rate of an isolated atrial preparation taken from the rat. The preparation was subject to atropine and atenolol both with and without the presence of ketamine. Where atropine produced an increase in heart rate of 16.5+6.1% the addition of and atenolol produced a decrease in heart rate of 15.5+3.2% where (p=0.085, n= 3, 3), the presence of ketamine was shown to inhibit these changes. The heart rate of the preparation was also tested immediately after vagal stimulation. The right vagus nerve was stimulated at a variety of frequencies where a stimulation of 20Hz for 30 seconds produced a decrease in heart rate of 32.3+2.6%, however, when this was repeated in the presence of ketamine, there was an increase in heart rate of 11.0+0.0% where (p=0.004, n=3,3). Ketamine showed similar results when tested on ganglionic transmission of isolated cardiac parasympathetic ganglia. It is believed that ketamine may have produced an increase in heart rate by bearing an inhibitory effect on parasympathetic receptors, where the agent has a greater affinity for nicotinic-AChRs over muscarinic-AChRs.