title: Renal nerve stimulation causes alpha 1-adrenoceptor-mediated sodium retention but not alpha 2-adrenoceptor antagonism of vasopressin.
abstract: Renal alpha 2-adrenoceptor stimulation by epinephrine infusion reverses cyclic adenosine monophosphate-mediated effects of vasopressin on sodium and water excretion. We used this response to determine whether renal nerve stimulation can activate renal alpha 2-adrenoceptors in the non-recirculating isolated perfused rat kidney (Krebs-Henseleit solution; 3.5 g/100 ml Ficoll; 1 g/100 ml albumin; 36 degrees C; propranolol 100 nM). In the presence of alpha 1-adrenoceptor blockade with prazosin (30 nM) alpha 2-adrenoceptor stimulation with epinephrine reversed the cyclic adenosine monophosphate-mediated effects of vasopressin on sodium (P less than 0.05) and water (P less than 0.05) excretion. Subthreshold (for vasoconstriction) renal nerve stimulation (10 V; 1 msec; 0.65 +/- 0.10 Hz) failed to alter the effect of vasopressin. Similarly, higher levels of renal nerve stimulation [plus prazosin (100 nM) or phenoxybenzamine (1.0 mg/kg per hr) to block alpha 1-adrenoceptors] did not activate renal alpha 2-adrenoceptors which are associated with the antagonism of the effects of vasopressin. The same level of subthreshold renal nerve stimulation (0.85 +/- 0.14 Hz) in the absence of vasopressin, and without alpha 1- or alpha 2-adrenoceptor blockade, decreased (P less than 0.05) sodium and water excretion. The reversal of this effect by alpha 1-adrenoceptor blockade (prazosin 30 nM) but not alpha 2-adrenoceptor blockade (yohimbine 300 nM) indicates that this effect of renal nerve stimulation is mediated through alpha 1-adrenoceptors. Thus, subthreshold renal nerve stimulation in the rat kidney induces sodium and water retention through activation of alpha 1-adrenoceptors, as shown by others in the rabbit and dog.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.forename: D D
authors.initials: DD
authors.lastname: Smyth
authors.forename: S
authors.initials: S
authors.lastname: Umemura
authors.forename: W A
authors.initials: WA
authors.lastname: Pettinger
mesh_terms: D000818:Animals; D001834:Body Water / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism; D004558:Electric Stimulation; D004837:Epinephrine / Q000494:pharmacology; D007668:Kidney / Q000098:blood supply / Q000294:innervation*; D008297:Male; D009318:Natriuresis; D010643:Phenoxybenzamine / Q000494:pharmacology; D011224:Prazosin / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D011942:Receptors, Adrenergic, alpha / Q000378:metabolism*; D012039:Regional Blood Flow; D014667:Vasopressins / Q000037:antagonists & inhibitors*; D015016:Yohimbine / Q000494:pharmacology
chemical_list: D011942:Receptors, Adrenergic, alpha; D010643:Phenoxybenzamine; D014667:Vasopressins; D015016:Yohimbine; D000242:Cyclic AMP; D011224:Prazosin; D004837:Epinephrine