Fluid balance in rats of three different strains after inhibition of histamine catabolism.
The effect of metoprine, an inhibitor of histamine (HA) catabolism, on fluid balance was studied in Wistar (W) and Long-Evans (LE) rats. AVP deficient Brattleboro (BB) rats were used to evaluate which phenomena were AVP-related. W and LE rats were quite different: LE rats were "dry" rats, they drank less, had higher plasma AVP, smaller urine volume and excreted more AVP, and responded less to salt loading and water deprivation. Furthermore, LE and W rats responded differently to metoprine. When water was provided as drinking fluid, metoprine increased water intake and urine flow in W rats, but these changes were not significant in LE rats. In contrast, when the rats drank saline, urine output and saline consumption were similarly decreased in LE and W rats. Although no metoprine-induced changes in plasma AVP were observed, urinary excretion of AVP per 24 h was reduced in metoprine treated rats. Inhibition of HA catabolism by metoprine caused only minor changes in fluid balance of AVP deficient BB rats. The results show that significant differences in fluid balance can exist between rat strains and that increased availability of HA after IP given metoprine strongly affects body fluids in normal rats, especially those of the W strain. The results provide further support to the involvement of HA in the regulation of fluid balance, but to obtain a more complete picture, other factors, such as atrial natriuretic peptide, should be studied.
Lecklin
A
A
Department of Pharmacology and Toxicology, University of Kuopio, Finland.
Tuomisto
L
L
D000818:Animals; D001127:Arginine Vasopressin / Q000172:deficiency / Q000378:metabolism; D001923:Brain Chemistry / Q000187:drug effects; D004326:Drinking / Q000187:drug effects; D006632:Histamine / Q000378:metabolism*; D008297:Male; D009994:Osmolar Concentration; D011188:Potassium / Q000378:metabolism / Q000652:urine; D011739:Pyrimethamine / Q000031:analogs & derivatives / Q000494:pharmacology; D051381:Rats; D011910:Rats, Brattleboro; D011919:Rats, Inbred Strains; D017208:Rats, Wistar; D012964:Sodium / Q000378:metabolism / Q000652:urine; D013045:Species Specificity; D014554:Urination / Q000187:drug effects; D014882:Water-Electrolyte Balance / Q000187:drug effects*
D001127:Arginine Vasopressin; C006308:metoprine; D006632:Histamine; D012964:Sodium; D011188:Potassium; D011739:Pyrimethamine