Effects of vasoactive intestinal polypeptide microinjected into the nucleus tractus solitarius on jejunal electrolytes absorption in rats.
It has been shown that vasoactive intestinal polypeptide (VIP) injected into the nucleus tractus solitarius inhibits alanine absorption across the jejunum. The aim of the present study was to investigate the effects of VIP injection into the nucleus tractus solitarius on jejunal absorption of electrolytes in the rat. Fifty-three Wistar rats were submitted to midline laparotomy to expose and isolate 20 cm of jejunal loop and to perform a subdiaphragmatic troncular vagotomy. Saline or VIP (10 pg 100 nl(-1)) was injected into the rostral nucleus tractus solitarius using a stereotaxic instrument. Tyrode solution, pH 8, containing twice glucose, sodium and potassium concentration was infused (0.5 ml min(-1)) into the jejunal loop. Samples were taken at 10-min intervals during the 40-min-experiment. Injection of VIP into the nucleus tractus solitarius increased jejunal potassium absorption. Moreover, VIP associated with vagotomy resulted in inhibition of jejunal potassium absorption by VIP alone at 40 min after perfusion (5.99 +/- 0.74 vs. 9.83 +/- 0.57 microM). There was no change in jejunal sodium absorption in any of the experimental groups. VIP had a modulatory action on jejunal potassium absorption when injected into the nucleus tractus solitarius.
Machado
Alvaro D C V
AD
Departamento de Fisiologia e Biofísica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil.
Haibara
Andréa S
AS
Petroianu
Andy
A
Borges
Elizabeth L
EL
D000818:Animals; D002555:Cerebrospinal Fluid; D004234:Diuretics, Osmotic / Q000494:pharmacology; D007408:Intestinal Absorption / Q000187:drug effects*; D007583:Jejunum / Q000294:innervation / Q000378:metabolism*; D008297:Male; D008353:Mannitol / Q000494:pharmacology; D008845:Microinjections; D011188:Potassium / Q000493:pharmacokinetics; D051381:Rats; D017208:Rats, Wistar; D012964:Sodium / Q000493:pharmacokinetics; D012965:Sodium Chloride / Q000494:pharmacology; D017552:Solitary Nucleus / Q000187:drug effects* / Q000502:physiology*; D013562:Sympathectomy; D014628:Vagotomy; D014660:Vasoactive Intestinal Peptide / Q000494:pharmacology*
D004234:Diuretics, Osmotic; D014660:Vasoactive Intestinal Peptide; D008353:Mannitol; D012965:Sodium Chloride; D012964:Sodium; D011188:Potassium