Effect of (1-24)adrenocorticotrophin on the uptake of 3H-norepinephrine by the rat atria.
Spontaneously beating rat atria were incubated with 3H-norepinephrine both in the presence and absence of (1-24)ACTH. A significant reduction in the uptake and retention of radioactivity was found in atria pretreated with (1-24)ACTH. A kinetic study of the uptake process showed similar Km values for both the control (24.1 x 10(-8) M) and (1-24)ACTH pretreated (22.2 x 10(-8) M) groups, but a significantly different Vmax. The Km values were similar to that reported for the neuronal reuptake process (Uptake 1). It was concluded that the ACTH-induced enhanced myocardial sensitivity to catecholamines previously reported, could be explained in part on the basis of an inhibition of neuronal uptake by (1-24)ACTH. The inhibition of neuronal uptake by (1-24)ACTH was dose-dependent.
Mehrabani
P A
PA
School of Biological Sciences, Macquarie University, N.S.W., Australia.
Bassett
J R
JR
D000324:Adrenocorticotropic Hormone / Q000494:pharmacology*; D000818:Animals; D006321:Heart / Q000187:drug effects*; D066298:In Vitro Techniques; D008297:Male; D009206:Myocardium / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism; D009638:Norepinephrine / Q000493:pharmacokinetics*; D051381:Rats; D011919:Rats, Inbred Strains
D000324:Adrenocorticotropic Hormone; D009638:Norepinephrine