Renal sympathetic nerve activation in relation to reserpine-induced depletion of neuropeptide Y in the kidney of the rat.
The effect of reserpine treatment on renal sympathetic nerve activity and tissue levels of neuropeptide Y (NPY)-like immunoreactivity (LI) and noradrenaline (NA) were studied in rats. Injection of reserpine (1 mg kg-1 i.v.) caused a clear-cut (about 50%) increase in rectified activity of the post-ganglionic sympathetic nerves to the kidney within 15 min in chloralose-anaesthetized rats compared to a saline-treated control group. This increase in nerve activity was still maintained 120 min after the reserpine injection. The renal nerve activation was accompanied by a progressive fall in mean arterial blood pressure and an initial tachycardia. In a separate group of conscious rats, the levels of NPY-LI (1.3 +/- 0.06 pmol g-1) and NA (1.6 +/- 0.07 nmol g-1) in the kidney were significantly reduced (by 74 and 83%, respectively) 24 h after reserpine treatment (1 mg kg-1 i.v.). The reserpine-induced depletion of NPY-LI, but not that of NA, was inhibited by pretreatment with the ganglionic blocking agent chlorisondamine or the alpha 2-adrenoceptor agonist clonidine, both of which are known to decrease renal sympathetic nerve activity. The tissue content of NPY-LI in the right atrium (16.3 +/- 0.7 pmol g-1) was not reduced by reserpine. Arterial plasma NPY-LI in the rat was high (222 +/- 5 pmol l-1), and this value did not change after pretreatment with reserpine, chlorisondamine or clonidine, indicating that, in the rat, circulating NPY-LI is not a good indicator of sympatho-adrenal activity.(ABSTRACT TRUNCATED AT 250 WORDS)
Pernow
J
J
Department of Pharmacology, Karolinska Institutet, Stockholm, Sweden.
Thorén
P
P
Millberg
B I
BI
Lundberg
J M
JM
D000818:Animals; D002714:Chlorisondamine / Q000494:pharmacology; D003000:Clonidine / Q000494:pharmacology; D007668:Kidney / Q000294:innervation* / Q000378:metabolism; D009478:Neuropeptide Y / Q000378:metabolism*; D009638:Norepinephrine / Q000378:metabolism; D051381:Rats; D011921:Rats, Inbred WKY; D012110:Reserpine / Q000494:pharmacology*; D013564:Sympathetic Nervous System / Q000187:drug effects*
D009478:Neuropeptide Y; D012110:Reserpine; D002714:Chlorisondamine; D003000:Clonidine; D009638:Norepinephrine