Differential sensitivity of regional vascular beds in the dog to low-dose prostacyclin infusion

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Abstract
The effect of low-dose prostacyclin (PGI2) infusion on abdominal organ, regional central nervous system, and regional myocardial blood flow distribution was studied in 14 open-chested, anesthetized dogs. Blood flow was measured using the radioactive microsphere technique and left atrial (LA) injection of 15-μm spheres. Continuous LA PGI2 infusion (25–35 ng/kg per minute) significantly (P < 0.05 to P < 0.005) increased renal cortical (+13%), splenic (+20%), small intestinal (+41%), large intestinal (+54%), fundic mucosal (+53%), and antral mucosal (+65%) blood flows whereas pancreatic, gallbladder, and hepatic (arterial) flow remained unchanged. Within the central nervous system blood flow increased in the medulla (+18%) and cerebral cortical gray matter (+17%) but was unchanged in the cervical spinal cord, pons, dorsal thalamus, cerebellum, caudate nucleus, and cerebral white matter. Atrial and ventricular myocardial blood flows and masseter muscle blood flow were unchanged during PGI2 administration. Thus blood flow changes are variable between and within regional vascular beds during low-dose PGI2 infusion in the dog.