Indomethacin enhances histamine-induced pulmonary hemodynamic changes

Area of Science:

• Physiology
• Pharmacology

Background:

• Histamine is known to induce changes in pulmonary hemodynamics.
• Prostaglandins play a role in regulating vascular tone.
• The specific role of prostaglandins in histamine-induced pulmonary responses requires further elucidation.

Purpose of the Study:

• To investigate the role of prostaglandins in mediating histamine-induced pulmonary hemodynamic alterations in pigs.
• To determine if inhibiting prostaglandin synthesis affects the pulmonary vascular response to histamine.

Main Methods:

• Anesthetized pigs were administered intravenous histamine.
• Pulmonary artery pressure, pulmonary arterial wedge pressure, left ventricular end diastolic pressure, and cardiac output were measured.
• Pulmonary arterial resistance and pulmonary venous resistance were calculated.
• Responses were compared with and without pre-treatment with indomethacin, a cyclo-oxygenase inhibitor.

Main Results:

• Histamine administration led to changes in pulmonary hemodynamics.
• Pre-treatment with indomethacin resulted in a 2-fold greater increase in pulmonary arterial and venous resistance in response to histamine.
• The increases in resistance were more prolonged after indomethacin pre-treatment.

Conclusions:

• Prostaglandins released from pulmonary endothelial cells normally act as vasodilators, opposing histamine-induced pulmonary vasoconstriction.
• Inhibition of prostaglandin synthesis potentiates histamine-induced pulmonary vasoconstriction and increases pulmonary resistance.