ROLE OF ATRIAL-NATRIURETIC-PEPTIDE IN DISTURBED WATER AND ELECTROLYTEMETABOLISM OF GUINEA-PIGS INFECTED WITH PICHINDE VIRUS

Daily intake and output of water and electrolytes (Na+, K+, and Cl-) w ere determined for 14 days in control and Pichinde virus-infected stra in-13 guinea pigs. Although water intake began to decrease 7 days afte r virus inoculation, total daily water output (insensible water loss, urine excretion, plus fecal water loss) had little change, However, in sensible water loss alone increased markedly in the virus infected ani mals. Both intake and excretions of urinary and fecal electrolytes dec reased at the middle (days 7 to 10) and late (days 11 to 14) stages of viral infection. Differences between intake and output of water and e lectrolytes were reduced significantly during these periods, To determ ine a possible relationship between atrial natriuretic peptide (ANP) a nd urinary Na+ and water excretion over intake, we measured plasma ANP concentrations. The mean control value of plasma ANP was 24 +/- 1.0 p g/ml, and plasma ANP concentrations of infected animals increased sign ificantly (P < 0.01) to 49.5 +/- 3.9 and 51.3 +/- 8.8 pg/ml on postino culation days 7 and 12, Because the overall physiologic responses to P ichinde virus infection are complicated, it is difficult to postulate a single central theme concerning the pathogenesis. Nevertheless, we h ypothesize that the virus-induced invisible tissue ''biochemical lesio ns'' and the consequential release of mediators and hormones were poss ible causes of death. Among other pathophysiologic mechanisms, the inc reased plasma ANP concentration may have played a role in the developm ent of disturbed water and electrolytes metabolism during Pichinde vir us infection.