The effect of various ions on uptake2 of catecholamines.
The effects of a decrease of the K+ gradient on the extraneuronal inward transport and outward movement of catecholamines were studied in rat heart, rabbit aortic rings and guinea-pig trachealis smooth muscle. Elevation of the extracellular K+ concentration caused a) inhibition of the corticosteroid-sensitive extraneuronal uptake (uptake2) of 3H-isoprenaline in rat heart and of 3H-noradrenaline in rabbit aorta, and b) acceleration of efflux of 3H-isoprenaline from rat heart, 3H-noradrenaline from rabbit aorta and adrenaline (measured by microphotometry) from guinea-pig trachealis muscle. In rat heart and rabbit aorta, the acute omission of one or the other of the ions Na+, Cl-, K+ or Ca2+ from the perfusion of incubation medium had no effect on initial rates of uptake2 of catecholamines, except that the absence of K+ had a small inhibitory effect in the rat heart. The prolonged absence of Na+, Ca2+ or K+ from the perfusion or incubation medium caused a marked inhibition of uptake2 of catecholamines. These inhibitory effects developed more quickly in rat heart than in rabbit aorta. These results are compatible with the possibility that either the K+ gradient across the cell membrane or the resting membrane potential is the force driving uptake2.
Bönisch
H
H
Bryan
L J
LJ
Henseling
M
M
O'Donnell
S R
SR
Stockmann
P
P
Trendelenburg
U
U
D000251:Adenosine Triphosphatases / Q000378:metabolism; D000818:Animals; D001011:Aorta / Q000378:metabolism; D001692:Biological Transport / Q000187:drug effects; D002118:Calcium / Q000502:physiology; D002395:Catecholamines / Q000378:metabolism*; D002713:Chlorine / Q000502:physiology; D005110:Extracellular Space / Q000378:metabolism; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007477:Ions; D008297:Male; D008564:Membrane Potentials; D008745:Methylation; D009206:Myocardium / Q000378:metabolism; D011188:Potassium / Q000502:physiology*; D011817:Rabbits; D051381:Rats; D012964:Sodium / Q000502:physiology; D014132:Trachea / Q000378:metabolism
D002395:Catecholamines; D007477:Ions; D002713:Chlorine; D012964:Sodium; D000251:Adenosine Triphosphatases; D011188:Potassium; D002118:Calcium