The effects of peptide and nonpeptide antagonists of angiotensin II receptors on the noradrenaline uptake of different brain structures in rats with angiotensin II-induced increase of water intake.
Angiotensin II (ANG II) significantly increased noradrenaline (NA) uptake by cortical, hypothalamic and hippocampal synaptosomes thus activating noradrenergic neurotransmission. ANG II did not affect NA uptake by striatal synaptosomes. The interaction between AT1 receptors and noradrenergic neurons and the involvement of brain noradrenergic neurotransmitter system in ANG II-induced drinking in rats is suggested by the increase of NA uptake in hypothalamus and frontal cortex which are rich in AT1 receptors and are of importance for drinking behavior. The ANG II-receptor antagonists losartan, EXP 3174, sarmesin and saralasin decreased NA uptake in all brain regions studied as compared to the uptake in the same brain regions of ANG II-injected animals thus antagonising the effect of ANG II. There is no relationship between the inhibition of ANG II-induced water intake and the changes of NA uptake under the effect of the ANG II-receptor antagonists.
Radioizotope Laboratory, Institute of Physiology, Bulgarian Academy of Sciences, Sofia, Bulgaria. fany@bio.bas.bg
S
S
Stancheva
L
L
Alova
M
M
Velkova
V
V
Georgiev
D000704:Analysis of Variance; D000804:Angiotensin II / Q000031:analogs & derivatives* / Q000494:pharmacology; D057911:Angiotensin Receptor Antagonists; D000818:Animals; D001921:Brain / Q000187:drug effects* / Q000378:metabolism; D004327:Drinking Behavior / Q000187:drug effects*; D007093:Imidazoles / Q000494:pharmacology; D019808:Losartan / Q000494:pharmacology; D008297:Male; D009638:Norepinephrine / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D012504:Saralasin / Q000494:pharmacology; D013777:Tetrazoles / Q000494:pharmacology
D057911:Angiotensin Receptor Antagonists; D007093:Imidazoles; D013777:Tetrazoles; D000804:Angiotensin II; C040420:angiotensin II, Sar(1)-Me-Tyr(4)-; C066026:losartan carboxylic acid; D012504:Saralasin; D019808:Losartan; D009638:Norepinephrine