The Effects of Beta Amyloid Peptide 1-42 on Isolated Rat Hearts and Ileum Smooth Muscle.

Neurotoxic beta amyloid peptides (βAPs) are involved in the pathogenesis of Alzheimer disease. βAP1-42 may also play a role in the regulation of cardiovascular functions. Therefore, we investigated the possible effects of βAP1-42 on isolated rat heart and ileum. The hearts were perfused with modified Krebs-Henseleit solution. Left ventricular developed pressure (LVDP), maximal rate of pressure development of left ventricle (+dP/dtmax), heart rate, coronary flow, monophasic action potential amplitude (MAPamp), MAP duration at 90% repolarization (MAP90) and contractions of ileum were measured. One, 10 and 100 nmol/l doses of βAP1-42 significantly decreased LVDP, +dP/dtmax and heart rate. The dose of 1 nmol/l did not change coronary flow, but 10 and 100 nmol/l doses significantly reduced it. All doses of βAP1-42 did not alter MAPamp, but increased MAP90. βAP1-42 (1, 10, 100, 1,000 nmol/l) also did not influence ileum contractions. We suggest that βAP1-42 produces negative inotropic and negative chronotropic effects with an increase in MAP duration. Furthermore, βAP1-42 at high doses decreases coronary flow.