Emetic, central nervous system, and pulmonary activities of rolipram in the dog.

Rolipram was characterized for its emetic, behavioral, cardiovascular and pulmonary activities in dogs, to assess its systemic pharmacology and potential bronchodilatory selectivity. At doses > or = 0.1 mg/kg i.

Phospholipid regulation of a cyclic AMP-specific phosphodiesterase (PDE4) from U937 cells.

The regulation of phosphodiesterase-4 (PDE4) by various phospholipids was explored using PDE4s partially purified from U937 cells. Preincubation (5 min, 4 degrees C) of the large molecular weight PDE4 denoted "Peak 2 PDE4" with mixed phosphatidic acids (PAs) produced a 2-fold increase in its Vmax without changing its Km (approximately 2 microM) for cyclic AMP. This "activation" was not limited to PAs with specific fatty acid substituents: Synthetic PAs containing saturated and/or unsaturated fatty acids 16-20 carbons long produced similar effects.

Rolipram inhibition of phosphodiesterase-4 activation.

Rolipram inhibited U937 cell phosphodiesterase-4 in either the presence or absence of saturating (100 micrograms/ml) phosphatidic acid in an apparently phospholipid-independent manner, exhibiting similar kinetics (Ki values = 0.41 and 0.59 microM, respectively).