Blocking Effects of Cyproheptadine and Methysergide upon Two Different Cardiovascular Responses to Serotonin

Academic Article


  • There are several different types of receptors which mediate responses by the cardiovascular system to serotonin. In this study we utilized 16 anesthetized dogs to compare the effects of cyproheptadine and methysergide upon two different cardiovascular responses to serotonin. Injection of serotonin (50-200 μg) into the right atrium produced pulmonary vasoconstriction during which the mean pulmonary artery pressure increased from 14 (±2) to 20 (±2) mm Hg (P < 0.05). As the same serotonin later reached the coronary circulation, a cardiogenic hypertensive chemoreflex is activated, causing systemic hypertension in which the mean aortic pressure promptly increases from 104 (±7) to 179 (±10) mm Hg. Administration of either cyproheptadine or methysergide eliminated the pulmonary hypertension, but only cyproheptadine was effective in blocking the cardiogenic hypertensive chemoreflex. The differential blocking effectiveness of these two serotonin antagonists suggests an important difference in physiological characteristics of the serotonin receptors involved. © 1980, SAGE Publications. All rights reserved.
  • Digital Object Identifier (doi)

    Author List

  • Hageman GR; James TN; Urthaler F
  • Start Page

  • 420
  • End Page

  • 423
  • Volume

  • 165
  • Issue

  • 3