Low-dose prostacyclin is superior to terbutaline and aminophylline in reducing capillary permeability in cat skeletal muscle in vivo

Objective: To analyze and compare the capillary permeability-reducing effec ts of prostacyclin, terbutaline, and aminophylline. Design: A prospective, experimental study. Setting: A university laboratory. Subjects: Fourteen adult, anesthetized cats. Interventions: The study was performed on an autoperfused calf muscle prepa ration enclosed in a plethysmograph, with continuous recordings of tissue v olume, arterial and venous blood pressures, and blood flow. The capillary f iltration coefficient was used as a measure of capillary hydraulic permeabi lity, and measured at different doses of intravenous infusions of prostacyc lin, terbutaline, and aminophylline. These analyses were made from normal a nd from raised permeability levels, the latter by prior and simultaneous in fusion of tumor necrosis factor-alpha (TNF-alpha) or histamine. All three o f the drugs analyzed were given at low doses, without vasodilator effect, a nd at doses with a clear vasodilator effect. Main Results: Prostacyclin infusion reduced capillary permeability to a val ue 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 coeffi cient when tested from the initial control permeability level. From a TNF-a lpha-raised permeability revel (about 50% above control) and from a histami ne-raised permeability level (about 60% above control), both drugs induced small reductions in the capillary filtration coefficient. Conclusion: Low-dose prostacyclin effectively reduces hydraulic capillary p ermeability in cat skeletal muscle and is superior to terbutaline and amino phylline.