Effects of Escherichia coli lipopolysaccharide on renal glomerular and tubular adenylate cyclase.

The effects of Escherichia coli lipopolysaccharide (LPS) on adenylate cyclase have been tested using renal tubular membranes and renal glomeruli isolated from rats. E. Coli LPS did not stimulate glomerular and tubular basal adenylate cyclase activity whereas it was an activator in the presence of fluoride. The effect of E. Coli LPS was immediate but was greater after 20 min preincubation. Maximum stimulation of both glomerular and tubular fluoride sensitive adenylate cyclase occurred at 125 microgram/ml of E. Coli LPS with an apparent Km (dose corresponding to 50% of maximum stimulation) of 30 microgram/ml. Above 125 microgram/ml there was a decrease in adenylate cyclase activity. E. Coli LPS produced an increase in the maximum velocity of both enzymes but did not affect their affinity for adenosine triphosphate. E. Coli LPS did not potentiate the effect of parathyroid hormone on glomerular and tubular adenylate cyclase. The lipid A moiety which is common to all LPS whatever the original strain gave results similar to those obtained with the entire LPS. This effect was specific and did not depend on the phospholipidic structure in general since no activation was obtained in the presence of phosphatidylserine.