Pentagastrin stimulates potassium absorption from the rat colon.

Pentagastrin is trophic to the colon but the physiologic effects of pentagastrin are incompletely known. We compared in vivo potassium (K+) absorption from the colons of pentagastrin-treated (PG, n = 13), sham (S, n = 12), and control (C, n = 3) Sprague-Dawley rats during continuous intraluminal K+ perfusion. Preoperative intraperitoneal injections were administered to PG (pentagastrin 0.25 mg/kg in 2 mL 0.9% NaCl q 12 h x 48 h) and S (2 mL 0.9% NaCl q 12 h x 48 h). Under xylazine anesthesia, cannulae were placed in the cecum, rectum, and femoral artery of each rat. Intraluminal perfusion was performed for 2 h at 30 mL/min with 40 meq/L KCl in 0.9% NaCl (PG and S) or 0.9% NaCl (C). We monitored serum sodium (Na+) and K+ every 15 min, and the affluent and effluent Na+ and K+ every 30 min. At each interval past 60 min, we observed higher serum K+ in PG compared with S and C (P less than .002) and higher K+ in S compared with C (P less than .05). No changes in serum Na+ occurred. We conclude that pentagastrin stimulates potassium absorption from the colon.