ObjectiveTo analyze and compare the capillary permeability-reducing effects of prostacyclin, terbutaline, and aminophylline.DesignA prospective, experimental study.SettingA university laboratory.SubjectsFourteen adult, anesthetized cats.InterventionsThe study was performed on an autoperfused calf muscle preparation enclosed in a plethysmograph, with continuous recordings of tissue volume, arterial and venous blood pressures, and blood flow. The capillary filtration coefficient was used as a measure of capillary hydraulic permeability, and measured at different doses of intravenous infusions of prostacyclin, terbutaline, and aminophylline. These analyses were made from normal and from raised permeability levels, the latter by prior and simultaneous infusion of tumor necrosis factor-alpha (TNF-alpha) or histamine. All three of the drugs analyzed were given at low doses, without vasodilator effect, and at doses with a clear vasodilator effect.Main ResultsProstacyclin infusion reduced capillary permeability to a value of about 25% below the initial control value, and this level was reached both from normal and increased permeability levels. The maximal reduction level was obtained at a low nonvasodilator dose of 2 ng/kg/min. Terbutaline and aminophylline had no significant effect on capillary filtration coefficient when tested from the initial control permeability level. From a TNF-alpha-raised permeability level (about 50% above control) and from a histamine-raised permeability level (about 60% above control), both drugs induced small reductions in the capillary filtration coefficient.ConclusionLow-dose prostacyclin effectively reduces hydraulic capillary permeability in cat skeletal muscle and is superior to terbutaline and aminophylline. (Crit Care Med 1999; 27:130-136)