“…infusion of ouabain, there was a differential tendency with respect to the total dose of ouabain be tween the appearance of tracheal constriction and bradycardia. In a previous report (12), we demonstrated that inhalation of histamine, over a range of concentrations from 0.000625-0.0025%, caused a vagal reflex induced tracheal constriction before there was a measurable change in blood pressure and heart rate. Although intracerebroventricular administration of histamine induced the vagal ly mediated tracheal constriction in guinea pigs (14) and dogs (15), there were no The change is significant at **P<0.01 when compared to the value of the control.…”