Uptake and release of 3-H-metaraminol by rat lung. Basic aspects, ionic and energy requirements.
The accumulation of 3H-metaraminol in incubated lung tissue of the rat was examined in vitro. Lung tissue concentrated tritium after incubation with 3H-metaraminol. This uptake proceeds against a concentration gradient and shows saturation kinetics (Km 12.5 X 10(-7) M and Vmax 2.105 nM/g/15 min.) with great affinity for 3H-metaraminol. The accumulation of 3H-metaraminol is dependent of temperature and energy supply, and requires the presence of sodium ions. The loss of accumulated radioactivity showed the possibility that a small fraction of metaraminol is apparently firmly boune (e.g. neuronal sites), while a greater portion is taken up by extraneuronal structures (e.g. capillary endothelial cells). The first localization could represent uptake-1 and the second uptake-2. The results obtained also confirm the important role of the lungs as an organ which participates in the fate of endogenous substances and drugs.
D000818:Animals; D003470:Culture Media; D004140:Dinitrophenols / Q000494:pharmacology; D004734:Energy Metabolism / Q000187:drug effects; D005260:Female; D005459:Fluorides / Q000494:pharmacology; D005947:Glucose / Q000494:pharmacology; D066298:In Vitro Techniques; D008168:Lung / Q000378:metabolism*; D008680:Metaraminol / Q000378:metabolism*; D051381:Rats; D012964:Sodium / Q000494:pharmacology; D013696:Temperature; D013997:Time Factors; D014316:Tritium
D003470:Culture Media; D004140:Dinitrophenols; D014316:Tritium; D008680:Metaraminol; D012964:Sodium; D005947:Glucose; D005459:Fluorides