Distribution and metabolism of exogenous somatostatin in the rat.
The mechanisms of clearance and degradation of injected [3H]somatostatin have been studied in the rat using octadecasilyl-silica extraction and HPLC separation methods.. Three apparent consecutive plasma half-lives of 1, 3 and 20 min were estimated following administration of a pharmacological dose. The initial rapid clearance was due to uptake by various tissue beds, mainly the large peripheral tissue masses muscle, skin and intestine which together accounted for 70% injected radioactivity at 1 min. By contrast the amounts taken up by liver and kidney were relatively small (less than 10%) despite the accumulation of higher concentrations. Massive degradation occurred following uptake and small fragments and amino acids were released into the circulation almost immediately. Inactivation by blood itself was negligible. A slow phase of decline observed at later times suggested a return of intact peptide from extravascular storage sites to sustain plasma concentrations.
D000818:Animals; D002851:Chromatography, High Pressure Liquid; D007700:Kinetics; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D013004:Somatostatin / Q000097:blood / Q000378:metabolism*; D014018:Tissue Distribution
D013004:Somatostatin