Pressure natriuresis and prostaglandin secretion by perfused rat kidney

Basal prostaglandin synthesis by the isolated perfused rat kidney

In order to assess the main characteristics of the prostaglandin (PG) biosynthesis by the isolated perfused rat kidney, the urinary and venous outputs of PGE2, PGF2alpha, 6-keto-PGF1alpha and of thromboxane (Tx)B2 were followed during 120 min after an equilibration period of 30 min. Single pass kidneys were perfused with a Krebs-Henseleit solution added with Polygeline at a constant flow rate providing a perfusion pressure about 90 mm Hg. From the beginning of the study, major differences could be observed in the renal biosynthetic rate of the 4 PG studied which were mainly excreted into the venous effluent. During the perfusion, urinary and venous outputs of PGE2, PGF2alpha and of TxB2 remained stable whereas those of 6-keto-PGF1alpha sharply increased and were found inversely related to the glomerular filtration rate (r = -0.95; p n 0.001). Finally, the urinary and venous outputs of each of the four PGs studied were found positively related. It is concluded that the isolated perfused rat kidney is a valuable preparation for studying the biosynthesis of PGs and that, at least in thi model, the urinary excretion of PGs is a good index of their renal synthesis.

Glomerular prostaglandin production in diabetic rats with renovascular hypertension

A rat model combining two-kidney, one-clip (2K1C) renovascular hypertension and streptozotocin-induced diabetes mellitus was used to assess the pathogenetic significance of vasodilator prostaglandins in diabetic glomerular injury. Glomeruli isolated from normotensive diabetic rats produced greater than normal amounts of PGE2 and 6-keto PGF1 alpha under in vitro incubation conditions. In 2K1C hypertensive-diabetic rats, glomeruli from unclipped kidneys (which are prone to accelerated diabetic glomerular injury) produced similarly elevated amounts of PGE2 and 6-keto PGF1 alpha, which significantly exceeded the levels produced by glomeruli from clipped kidneys (which are relatively protected from glomerular injury), despite exposure to a similar diabetic environment. In contrast, glomeruli from both unclipped and clipped kidneys of 2K1C hypertensive-non-diabetic rats produced normal amounts of PGE2 and 6-keto PGF1 alpha. These results suggests a correlation between vasodilator prostaglandin metabolism and susceptibility to diabetic glomerular injury, and illustrate that enhanced glomerular prostaglandin production is not an invariable metabolic consequence of hyperglycemia or insulin deficiency. The data also demonstrate that hemodynamic as well as metabolic factors may influence glomerular prostaglandin metabolism in experimental diabetes mellitus.

Isolated perfused rat kidney and liver combined. A new experimental model

Interaction between hepatic and renal metabolism is found in many endocrine systems. We therefore developed a new experimental model, combining the isolated perfused rat kidney and rat liver. Krebs-Henseleit buffer with bovine serum albumin 67 g X l-1 and amino acids was recirculated to both organs through two rolling pumps, four 8 microns Millipore filters and two specially designed membrane lungs. The kidney was cannulated by a modification of the technique described by Nishiitsutsuji-Uwo 1967 and the liver was cannulated by a modification of the technique described by Hems 1966. Kidney function: Perfusion pressure 12.4 +/- 1.1 kPa (93 +/- 8 mmHg), flow 28 +/- 6 ml X min-1 X g-1, FRNa 94.0 +/- 2.9%, GFR 491 +/- 191 microliters X min-1 X g-1, urine production 48 +/- 34 microliters X min-1 X g-1, FEK 60 +/- 36%. Liver function: Flow 25 ml X min-1 (fixed), portal vein pressure 12 +/- 3 cm H2O, bile flow 0.18 +/- 0.13 ml X h-1, oxygen consumption 2.0 +/- 0.2 mumol X min-1 X g-1. Only minor differences were found between single perfusions (N = 25) and combined perfusions (N = 6). We conclude that it is possible to combine the isolated perfused rat kidney and rat liver without impairment of the function of either.