thromboxane-a2 and Respiration-Disorders

Cardiorespiratory variables were measured continuously in five conscious goats before and after the infusion of U-46619 at a dose of either 2, 4, or 6 micrograms.kg-1.5 min-1. Infusion of U-46619 led to immediate increases in pulmonary arterial blood pressure (ABP) that were sustained for up to 15 min after the end of the infusion. Systemic ABP also increased, but the relative increase from control was less than the pulmonary pressor response. At the highest dose, U-46619 elicited a delayed tachypneic response that was greatest several minutes after the infusion was stopped. U-46619 was also infused simultaneously with sodium nitroprusside to clamp ABP pressure at baseline levels to determine whether stimulation of baroreceptors might contribute to the latency of the tachypneic response. Although sodium nitroprusside infusion prevented the increase in ABP, the increase in breathing frequency was still delayed 3-4 min from the start of the infusion. We conclude that U-46619 elicits pulmonary and systemic arterial hypertension in the conscious goat. At the higher dose U-46619 also elicits a delayed tachypnea that remains delayed even if ABP is normal.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Blood Gas Analysis; Blood Pressure; Female; Goats; Hypertension; Hypertension, Pulmonary; Nitroprusside; Phenylephrine; Pressoreceptors; Prostaglandin Endoperoxides, Synthetic; Respiration Disorders; Respiratory Mechanics; Thromboxane A2; Vasoconstrictor Agents