The effects of transmitters on the affinity of the insoluble fraction of ox brain for Na+ and K+.
The insoluble fraction of ox-brain, which had previously been shown to have a non-linear affinity for Na+ and K+, was prepared. Acetylcholine (1 x 10(-8) mol/l and 1 x 10(-7) mol/l) reduced the affinity of the fraction for Na+ and K+ to zero, while at 1 x 10(-6) mol/l, the affinity for the cations was almost as high as in the absence of the transmitter; the affinities for Na+ and K+ were particularly high, when the supernatant concentrations of these ions exceeded 80-100 mM. Addition of eserine (3 x 10(-5) mol/l) considerably modified the response of the fraction to acetylcholine (1 x 10(-5) mol/l). Atropine (1 x 10(-8) mol/l) in the absence or presence of acetylcholine (1 x 10(-5), or 1 x 10(-4) mol/l) reduced the affinity of the fraction for Na+ and K+ to zero. Epinephrine (3 x 10(-10) mol/l) lowered the affinity for Na+ and K+, while ergotamine itself (1 x 10(-5) mol/l) reduced it to zero. The addition of both epinephrine and ergotamine at the latter concentrations restored the affinity of the fractions for Na+ and K+ to what it had been in the absence of the transmitter or antagonist, previously reported. Norepinephrine (3 x 10(-10) mol/l), or ouabain (1 x 10(-7) mol/l) reduced the affinity of the fraction for Na+ and K+ to zero. Thus, the transmitters and antagonists altered the affinity of the insoluble fraction for Na+ and K+ non-linearity, dependent upon their concentrations, the concentrations of the cations, and the interaction of transmitter and antagonist.
Ahmed
N
N
Unity Laboratory of Applied Neurobiology, University of Surrey, Guildford, England.
Hillman
H
H
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D002417:Cattle; D004837:Epinephrine / Q000494:pharmacology; D004878:Ergotamine / Q000494:pharmacology; D007700:Kinetics; D018377:Neurotransmitter Agents / Q000494:pharmacology*; D009638:Norepinephrine / Q000494:pharmacology; D010042:Ouabain / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism*
D018377:Neurotransmitter Agents; D010042:Ouabain; D001285:Atropine; D012964:Sodium; D000109:Acetylcholine; D004878:Ergotamine; D011188:Potassium; D009638:Norepinephrine; D004837:Epinephrine