ROLE OF ATRIAL-NATRIURETIC-PEPTIDE IN INTERLEUKIN 1-BETA-INDUCED NATRIURESIS IN CONSCIOUS RATS

To assess whether atrial natriuretic peptide (ANP) plays a role in the natriuresis induced by interleukin 1 beta (IL-1 beta), the following experiments mere carried out. Experiment (Ex) I: IL-1 beta (7.5 mu g/k g BW) was given intravenously (i.v.) in conscious hydrated rats (n=6). Plasma ANP, vasopressin (AVP) osmolality (P-osm), Na and K, urine Na (UNaV) and K excretion (UkV), osmolality and flow (UF), and mean arter ial blood pressure (MABP) and heart rate were simultaneously determine d. In the control group (n=6), the drug was omitted, and the same prot ocols mere carried out. Ex II: Three mg/kg BW of the specific ANP anta gonist, HS-142-1 (HS), was administered i.v. and then, IL-1 beta (7.5 mu g/kg BW) mas given i.v. (n=6). In the KS alone group (n=6), IL-1 be ta was omitted. The experimental protocols were the same as those in E x I. IL-1 beta increased significantly plasma ANP and AVP and UNaV, bu t not UF, accompanied by decreases in P-osm and UKV and increases in M ABP (ExI). EIS inhibited the natriuresis mediated by IL-1 beta, despit e increases in plasma ANP and had no influence on plasma AVP and MABP. In the control (ExI) and KS alone (ExII) groups, these parameters did not change, except for decreases in Posm in both groups and increased plasma ANP in the latter. These results suggest that plasma ANP may p lay an essential role in the IL-1 beta-mediated natriuresis.