AJP - Heart and Circulatory Physiology, Vol 246, Issue 6 747-H753, Copyright © 1984 by American Physiological Society
Effects of thrombocytopenia on monocrotaline pyrrole-induced pulmonary hypertension
K. S. Hilliker, T. G. Bell, D. Lorimer and R. A. Roth
Monocrotaline pyrrole (MCTP) causes lung injury, pulmonary hypertension,
and right ventricular hypertrophy in rats. To determine if platelets are
involved in the cardiopulmonary effects of MCTP, the response to MCTP was
determined in thrombocytopenic rats. Blood platelet count was reduced to
10-20% of normal for 48 h by ip administration of an antirat platelet serum
(PAS) prepared in the goat. Rats were treated iv with either MCTP 5 mg/kg
or dimethylformamide vehicle and with either PAS or preimmune serum.
Fourteen days after MCTP, right ventricular hypertrophy and several indexes
of lung injury were measured. MCTP treatment produced right ventricular
hypertrophy, increased lactate dehydrogenase activity and protein
concentration in bronchopulmonary lavage fluid, increased perfusion
pressure in isolated lungs, and decreased pulmonary clearance and
metabolism of perfused 5-hydroxytryptamine. Thrombocytopenia did not
influence the changes in these indexes of lung injury produced by MCTP in
this protocol. When PAS was given 12 h before MCTP, it did not affect right
ventricular hypertrophy, but when PAS treatment was begun 3 or 6 days after
MCTP, right ventricular hypertrophy was decreased by 19 or 41%,
respectively. These results suggest that platelets help to mediate the
development of pulmonary hypertension and the hypertrophic response of the
right heart following MCTP administration.
