Does secretin influence rat colonic absorption and secretion?

In rats, a secretin (Jorpes) intravenous infusion superimposed on an intracolonic sodium acetate perfusion elicits, with respect to control values, a significant depression of Na+ absorption (0.16 mEq./h-0.00 mEq./h.) and mucus secretion (230-40 mg.). When the hormone is superimposed upon an intracolonic infusion of acetic acid, mucus secretion is also significantly inhibited (790-340 mg.). The influence of secretin on organic anion movement was pH related. At pH values of 7.0, absorption was unchanged (0.34--0.33 mEq./h.), at pH values of 2.9, absorption was significantly reduced (0.67-0.41 mEq./h). The secretin impairment of colonic mucus secretion could influence the transport of watersoluble (Na+) and lipid soluble (acetic acid) substances, probably through changes at the "unstirred layer" level.