Pentagastrin Stimulates Potassium Absorption from the Rat Colon

Abstract

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% NaClq 12h × 48 h) and S (2 mL 0.9% NaClq 12 h × 48 h). Under xylazine anesthesia, cannulae were placed in the cecum, rectum, and femoral artery of each rat. Intraluminal perfusion was performed for 2 hat 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 <. 002) and higher K⁺ in S compared with C (P <. 05). No changes in serum Na⁺ occurred. We conclude that pentagastrin stimulates potassium absorption from the colon.

Key Words:

• Gastrin
• pentagastrin
• colon
• potassium absorption