[Mitral valve disease and atrial natriuretic polypeptide].

We compared plasma ANP concentration and atrial content of ANP as well as plasma concentrations of other fluid regulating hormones and renal function between the MVR group (n = 12) and the non MVR group (n = 14) during open heart surgery. Preoperatively there was no significant difference in plasma ADH and ACTH between two groups, however plasma ANP was significantly higher in the MVR group (96.9 +/- 16.2 pg/ml) than in the non MVR group (22.8 +/- 8.6 pg/ml) (p less than 0.01). During extracorporeal circulation ANP was at a low level because of aortic clamping. Tissue concentration of ANP in right appendages was higher (p less than 0.02) in the MVR group (61.8 +/- 11.8 nmol/g wet weight) (n = 6) than that in the non MVR group (14.9 +/- 3.1 nmol/g wel weight) (n = 15). Also, concentration in left appendages of the MVR group (50.0 +/- 10.4 nmol/g wet weight) (n = 4) was higher than that in right appendages of the non MVR group (p less than 0.05). From these results it may be concluded that increased secretion of ANP is elicited by left atrial load and probably playing an important role on circulating blood volume regulation.