Characterization of fluorescein transport in isolated proximal tubular cells of the rat: evidence for mitochondrial accumulation.

The uptake and accumulation of the organic anion fluorescein-sodium (Flu-Na) was investigated in freshly isolated proximal tubular cells (PTC) of the rat kidney. Furthermore, the influence of other organic anions on Flu-Na uptake was studied in order to characterize Flu-Na transport in PTC. Flu-Na showed concentration-dependent, saturable and probenecid-sensitive transport. Comparing the transport parameters with para-aminohippurate (PAH), Flu-Na exhibited a higher affinity, but lower capacity to the organic anion transport system. The apparent Km for Flu-Na transport was 59 +/- 15 microM with a Vmax of 186 +/- 26 pmol/mg of protein/min, and for PAH 207 +/- 11 microM and 740 +/- 46 pmol/mg of protein/min, respectively. Dose-dependent inhibition of Flu-Na uptake with PAH resulted in an apparent inhibition constant Ki of 249 microM. This is in good agreement with the apparent Km of PAH, indicating that Flu-Na uptake is regulated by the PAH transport system. It is suggested that cellular uptake of both organic anions is mediated by a carrier at the basolateral membrane. However, after incubating cells with different concentrations of phenol red the percentage of maximum inhibition was 84%, which was significantly different from the 32% with PAH, suggesting that another transport system may be involved in Flu-Na uptake. Experiments with confocal laser scanning microscopy showed cellular uptake of Flu-Na and accumulation in subcellular structures. After superfusion of PTC with rhodamine 123 these structures were identified as mitochondria.

[Are the long-term results of venous aortocoronary bypass procedures really so bad? A prospective 13-year-long study of 428 patients]. / Zijn de lange-termijnresultaten van veneuze aortocoronaire overbruggingsoperaties wel zo slecht? Een prospectief onderzoek over 13 jaar bij 428 patiënten.

OBJECTIVE: To assess the long-term results of coronary surgery using venous bypasses. DESIGN: Prospective study. SETTING: St. Antonius Hospital, Nieuwegein, the Netherlands. METHOD: In 446 successive patients subjected to coronary surgery between 1 April 1976 and 1 April 1977, a complete long-term follow-up study was carried out after an average of 11.5 years (1.5 months-14.3 years). RESULTS: The peroperative mortality was 3%, a peroperative myocardial infarction occurred in 6.3% and complete revascularization was achieved in 77.6% of the patients. In 90 of 100 patients selected at random, cardiac catheterization was performed 13.5 months on average after the operation. The patency of the single grafts was 89.8%, that of the side-to-side and end-to-side anastomoses of the sequential grafts was 90.4% and 83%, respectively. Mortality, myocardial infarction, necessity of a second operation and angina pectoris occurred with low frequency during the first five years after the operation. Subsequently, complications increasingly occurred. Ten years after the operation 18.8% of the patients had died, 11.9% had suffered a myocardial infarction, 13.4% had been subjected to a second operation and 6.4% to balloon angioplasty, while 46.4% had once more developed angina pectoris. Thirteen years after the operation 29% of the patients had remained completely free from cardiac problems. CONCLUSION: Although arterial bypasses have been increasingly used in recent years, an indication for the use of venous transplants will continue to exist in the future, also, for certain groups of patients (those younger than 50 or older than 75 years). Our study clearly shows that with venous bypasses, also, satisfactory long-term results can be obtained.