Heart failure mice exhibit decreased gastric emptying and intestinal absorption

Our recent study showed that intravenously administered B-type natriuretic peptide (BNP) decreases gastric emptying and intestinal absorption in mice. We aimed to test whether acute myocardial injury and heart failure have similar effects. Wild-type (WT) and natriuretic peptide receptor type A (NPR-A) knockout (KO) mice underwent cryoinfarction (myocardial infarction MI) of the left ventricle (LV) versus sham. LV dysfunction was confirmed by echocardiography. Percent gastric emptying and intestinal absorption were measured and analyzed one and two weeks after infarction, by gavage feeding the mice with fluorescein-isothiocyanate-dextran. Ejection fraction was 48 ± 3% versus 64 ± 2% (P < 0.05) and fractional shortening was 24 ± 2% versus 35 ± 2% (P < 0.01), MI versus sham, respectively. BNP levels (pg/mL) were 4292 ± 276 one week after MI versus 105 ± 11 in sham (n = 5, P < 0.05) and 1964 ± 755 two weeks after MI (n = 5, P < 0.05). Gastric emptying was significantly decreased, 68 ± 6% in MI versus 89 ± 3% in sham (n = 5, P < 0.05) one week after MI and 82 ± 0.5% versus 98 ± 0.4%, MI versus sham (n = 5, P < 0.05), two weeks post-MI. Absorption, measured in relative plasma fluorescence units in WT mice, was 350 ± 79 in MI versus 632 ± 121 in sham (n = 6, P < 0.05). KO mice did not show a significant difference in emptying or absorption compared with sham. These findings suggest that MI and LV dysfunction decrease gastric emptying and absorption in mice through a mechanism that involves NPR-A.