Figure 7.

The serotonin type 2 receptor antagonists, mianserin and ketanserin, are not effective inhibitors of serotonin-stimulated increases in heart rate. (A) Sample traces of 5 μM mianserin application in isolation and in the presence of 100 nM serotonin. (B) Sample traces of 5 μM ketanserin application in isolation and in the presence of 100 nM serotonin. Black bars denotes application of antagonist or antagonist with serotonin at specified concentrations, trace to the left of the black bar represents spontaneous myogenic contractions in saline and to the right of the black bar is the response to serotonin or agonist application. (C,D) Bar graph summary of the frequency of heart contractions (beats/min) under saline, serotonin alone, single antagonists alone or in combination with serotonin. Columns marked with different letters are significantly different (ANOVA, Tukey-Kramer multiple comparison test, P < 0.05). Data points are means ± standard error (n = 6 for each data point for assessments with mianserin and ketanserin; n = 9 for each data point for assessments with gramine).