Kaj Anker Jorgensen

Antagonist capacities of nifedipine, captopril, phenoxybenzamine, prostacyclin and indomethacin on cyclosporin A induced impairment of rat renal function

Abstract. Experimental evidence indicates that cyclosporin A (CyA) nephrotoxicity is due to renal arteriolar constriction, reducing renal blood flow, glomerular filtration rate (GFR), and delivery of tubular fluid from the end of the proximal tubule to the loop of Henle. The proximal tubular fractional reabsorption (PFR) is increased. Therefore, the impact on renal function of vasodilating agents was studied in rats given CyA. Conscious catheterized rats and clearance techniques were used. In acute experiments a preexisting CyA‐nephrotoxicity was resistant to infusion of phenoxybenzamine, prostacyclin, captopril, nifedipine and indomethacin. Concomitant treatment with captopril and CyA did not improve renal function, while concomitant treatment with CyA and nifedipine improved GFR to 1·13±0·34 ml min‐1 g‐1 kidney weight (gKW) (n=19, P<0·05), as compared to CyA and placebo treated controls (n=12, 0·83±0·32 ml min‐1 g‐1 KW). Nifedipine also reduced FPR (88·6±5·1% vs. 83·2±5·6%. P<0·01), and increased lithium clearance from 99±54 to 184±64 μl min‐1 g‐1 KW (P<0·001). The results are further evidence that CyA nephrotoxicity includes renal vasoconstriction, and indicates that calcium entry blockade is nephroprotective in the case of CyA toxicity.

The survival of pig to rabbit renal xenografts during inhibition of thromboxane synthesis

Five rabbits treated with the thromboxane synthetase inhibitor Dazoxiben and five control rabbits received pig renal xenografts. Plasma albumin, complement factor C3, TXB2, 6-keto-PGF1 alpha, and serum TXB2 and 6-keto-PGF1 alpha were determined before and 1/2 hour after transplantation. The xenograft survival was significantly decreased in the Dazoxiben treated animals compared to the placebo treated animals determined as time to total cyanosis of the graft, total urine production, and time to stop of urine production. Lack of TXB2 production during blood coagulation confirmed inhibition of platelet thromboxane synthesis. The other determined variables showed no significant differences between the treated and the placebo animals.

Development of Anti-OKT3 Antibodies After OKT3 Treatment

The development of IgG and IgM anti-OKT3 antibodies the first 90 days after start of OKT3 treatment for acute cellular rejection was determined by ELISA in 25 consecutive renal transplant patients. The ELISA positive sera were then tested for neutralizing OKT3 antibodies by immunofluorescence inhibition assay utilizing the FACScan. The number of IgM positive patients was highest, four (16%) after 10 days of treatment and then declined. The highest number of patients, thirteen (56%) with IgG antibodies was found after 60 days. Sera with only IgM antibodies or with low IgG titers (< 1:100) did not neutralize OKT3. Five patients (20%) developed neutralizing antibodies. All of these patients had received OKT3 during an earlier transplantation. In four of these patients, the ACR had been reversed successfully before the development of antibodies, and in the last patient the ACR was reversed by a second course of Minnesota-ALG and increasing the dose of Cyclosporine. Monitoring the development of neutralizing anti-OKT3 antibodies is valuable in patients who have previously received OKT3 treatment.

Platelet aggregation is not essential for xenograft rejection

Five rabbit kidneys were perfused at 80 mm Hg with heparinized human blood, five with platelet poor human blood, and five with human blood added prostacyclin. Time until blood flow decreased to 2 ml/min was significantly delayed by removal of platelets or addition of prostacyclin. Histological examination did not reveal any difference between the groups. It is concluded that platelets play an enhancing role, but they are not essential for xenograft rejection.

Analysis of the inflammatory leucocyte mobilization in 838 fine needle aspiration biopsies in non-rejecting (day 1–90) kidney grafts and 465 biopsies in grafts before, during and after acute cellular rejection

A total of 1303 fine needle aspiration biopsies (FNABs) were performed in all 105 kidney transplanted patients at our institution during 1990-1992: 838 were in patients who never had an acute cellular rejection (ACR), and 465 were in patients who had experienced an ACR; 393 of these FNABs were performed in first rejections and 72 in second rejections. The immunosuppressive protocol included monotherapy with cyclosporin A and an initial, additional course of Minnesota-ALG during the first ten days after transplantation (Tx). OKT3 was first-line antirejection therapy accompanied for a short period with prednisolone and azathioprine to oppose the development of anti-OKT3 antibodies. FNABs were taken each day for the first three days after Tx, then twice a week for the first month, and then at each visit to the outpatient clinic for the next three months. In non-rejecting grafts the total corrected increment (median) of the inflammatory response (TCI) increased from 1 to a maximum of 3.5, 17-21 days after Tx followed by a slight decrease. The inflammatory response was mainly due to non-activated lymphocytes. In the rejecting grafts the TCI (median) increased from three days before ACR to a maximum of 7 on the day of ACR, followed by a decrease when OKT3 treatment was started. The infiltrating cells were activated lymphocytes, other lymphocytes and, in smaller amounts, macrophages and monocytes.

Pinacidil - Effects on Function and Perfusion of Normal Kidneys and Renal Xe nog rafts

Pinacidil is a new vasodilating compound claimed to increase renal perfusion and function. A preliminary study showed that pinacidil did not sustain renal perfusion through a period of increasing renal vascular resistance in pig-to-rabbit renal xenotransplantation. Accordingly, the effect of pinacidil on renal function in conscious catheterized rats was studied. Pinacidil 0.12-0.18 mg/kg i.v. caused a moderate reduction in mean arterial blood pressure (14-17 mmHg), a decrease in inulin and PAH clearances (50-65%), and sodium and water retention. The sodium clearance/lithium clearance ratio decreased, suggesting increased sodium reabsorption in the distal nephron during pinacidil administration. Thus the results are in accord with those obtained with several other vasodilators, but not with those obtained in mongrel dogs during pinacidil administration.

Activation of fibrinolysis during xenoperfusion.

Ten rabbit kidneys were perfused at 80 mm Hg, 37 degrees C, with oxygenated recirculating heparinized human blood. These experiments were compared to another ten perfusion experiments where 1 unit/ml porcine plasmin was added to the human blood one hour before the perfusion, at which time the fibrinolytic activity was significant and the fibrinogen concentration under the detection limit. Rejection, determined as time until blood flow decreased to 2 ml/min, was not significantly delayed by addition of plasmin. At the end of the experiments, the fibrinolytic activity in the control experiment had increased above the activity in the plasmin added experiments, although the fibrinogen concentration was almost unchanged. Histological examinations demonstrated a decreased platelet deposition and the fall in platelet count was smaller in the plasmin experiments. C3d determinations revealed a slight activation of complement upon addition of plasmin, but the activation by xenoperfusion was much more pronounced and, at the end of the experiment, the C3d concentration was the same in the two groups.

Flush Perfusion of Rabbit Kidneys with Autogeneic, Allogeneic and Xenogeneic Blood

A simple perfusion model was developed to study the events that lead to rejection of renal xenografts. Flush perfusion of the kidneys of 24 rabbits was carried out with blood from rabbits, cats, or humans. Light microscopy showed alterations with neutrophilic granulocytes margination of the vessels after only 15 min of perfusion. In the experiments with human blood the immunofluorescence microscopy showed deposits of immunoglobulins and complement factor III. This simple method is therefore a useful way of studying perfusion in renal xenografts.