EFFECT OF SEPTICEMIA ON THE PLASMA-LEVELS OF BIOPTERIN AND NITRIC-OXIDE METABOLITES IN RATS AND RABBITS

Live Escherichia coli decreased mean arterial blood pressure in rabbit s from 67 to 20 mmHg. E. coli did not affect blood pressure in rats bu t did significantly increase heart rate by 29%. To relate the cardiova scular effects with putative relevant biochemical pathways, the plasma levels of nitrate + nitrite (NOx) and biopterin, representing the mai n metabolites of nitric oxide and tetrahydrobiopterin, respectively, w ere determined in conscious rats and rabbits after treatment with live E. coli. In rats, E. coli induced a rapid 43% increase in the plasma level of biopterin preceding the 7 to 26-fold increase in NOx level. I n rabbits, no increase in the NOx level was observed despite a 3- to 5 -fold increase in the biopterin level at 6-10 hr posttreatment. It is concluded that the synthesis of tetrahydrobiopterin precedes nitric ox ide synthesis after induction of septicaemia in the rat. After the ind uction of septicaemia, rabbits show a clear hypotensive response and a n increase in biopterin level but no concomitant increase in NOx. Biop terin apparently represents a more appropriate biochemical marker of s eptic shock than does NOx. Copyright (C) 1996 Elsevier Science Inc.