EFFECT OF LUNG TRANSIT ON SYSTEMIC DEPRESSOR RESPONSES TO ARACHIDONIC-ACID AND PROSTACYCLIN IN DOGS

  • 1 January 1978
    • journal article
    • research article
    • Vol. 204  (2) , 289-293
Abstract
Arachidonic acid (AA) (100 and 200 .mu.g/kg) and prostacyclin (PGI2) (0.25, 0.5, 1,2 and 3 .mu.g/kg) were administered by bolus injection into the inferior vena cava (i.v.) and left ventricle (i.a.) in 25 spontaneously breathing anesthetized dogs. PGI2, like its precursor AA, decreased arterial diastolic pressure in a dose-dependent manner. Depressor responses after i.a. administration of a given dose of either AA or PGI2 did not differ significantly when the same dose was given i.v.; the i.v./i.a. ratio was 1. In comparison, the vasodepressor response to PGE2 (1, 2 and 3 .mu.g/kg i.v.) was reduced 12- to 40-fold by passage through the dog lung. The vasopressor response to PGF2.alpha. (1, 2, 3 and 5 .mu.g/kg i.v.) was diminished 5- to 8-fold by lung transit. The pressor response to norephinephrine was reduced by pulmonary transit. Apparently the lung plays a minor role in the systemic depressor response to AA and PGI2, and the lack of an i.v./i.a. difference for AA and PGI2 indicates that the depressor response to AA may be due to generation of PGI2 by the vessel wall.