The effect of atrial natriuretic peptide on small intestinal contractility and transit.
Isometric tension in response to ANF (10(-10) to 10(-4) M) was recorded from longitudinally and circularly oriented rat jejunal smooth muscle strips. Conscious, fasted rats received an IV infusion of 1.25 nmol ANF/100 g body weight in 0.5 ml normal saline and controls received saline alone. Five minutes later 10 muCi Na2 51CrO4 in 0.5 ml saline was instilled through a jejunostomy. Fifteen minutes later animals were sacrificed, and the gut divided into 8 equal segments of small intestine, cecum and remaining colon. The radioactivity of each segment was measured and a geometric center of transit determined for each group. ANF induced relaxation of longitudinally oriented strips (Tm = -72.3 +/- 10.7 mN/g, ED50 7.3 +/- 3.6 x 10(-8) M), and contraction of circularly oriented strips (Tm = 35.0 +/- 5.0 mN/g, ED50 1.3 +/- 1.0 x 10(-8) M). This response was unaffected by 10(-6) M tetrodotoxin. The geometric mean center of transit was significantly (p less than 0.001) further aboral in ANF-treated compared to control animals (intestinal segment 4.2 +/- 0.2 vs. 3.2 +/- 0.2).
Scott
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RB
Gastrointestinal Research Group, University of Calgary, Alberta, Canada.
Maric
M
M
D000818:Animals; D009320:Atrial Natriuretic Factor / Q000494:pharmacology*; D005769:Gastrointestinal Motility / Q000187:drug effects; D066298:In Vitro Techniques; D007583:Jejunum / Q000187:drug effects / Q000502:physiology; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects; D051381:Rats
D009320:Atrial Natriuretic Factor