K. Shinozuka et al., DIFFERENCES IN PURINOCEPTOR MODULATION OF NOREPINEPHRINE RELEASE BETWEEN CAUDAL ARTERIES OF NORMOTENSIVE AND HYPERTENSIVE RATS, The Journal of pharmacology and experimental therapeutics, 272(3), 1995, pp. 1193-1198
The effects of 2-chloroadenosine, a purinoceptor agonist, on the overf
low of endogenous norepinephrine (NE) was examined in the electrically
field-stimulated (EFS) caudal artery obtained from Wistar-Kyoto (WKY)
rats and age-matched spontaneously hypertensive rats (SHRs). 2-Chloro
adenosine at 10(-6) and 10(-5) M reduced the EFS-evoked release of NE
from arteries of WKY rats but was without effect on the release of NE
from arteries of SHRs. Methoxamine (10(-5) M), an alpha adrenoceptor a
gonist, caused the release of ATP, ADP, AMP and adenosine from caudal
arteries of Wistar rats, WKY rats and SHRs, and decreased the release
of EFS-evoked release of endogenous NE in arteries from normotensive r
ats, but not from arteries of SHRs. Thus, both exogenously applied and
endogenously released purines are ineffective in reducing the evoked
release of NE in this model of hypertension. The enhanced release of N
E from sympathetic nerves of SHRs may be due in part to the loss of pr
ejunctional modulation by purines.