Substance P effects on blood flow, fluid transport and vasoactive intestinal polypeptide release in the feline small intestine.
AUTOR(ES)
Brunsson, I
RESUMO
1. Substance P (SP) infusions were given close I.A. to the feline small intestine in vivo in a dose that produced plasma concentrations of 1-5 microM. This infusion regularly evoked a net fluid secretion measured with a gravimetric technique. Concomitantly, the release into blood of vasoactive intestinal polypeptide (VIP), a putative neurotransmitter of the enteric nervous system, increased. 2. The SP-induced fluid secretion was blocked by tetrodotoxin (7 micrograms close I.A.), a blocker of fast sodium channels in excitable tissues, and hexamethonium (10 mg (kg body wt)-1, I.V.), a nicotinic receptor antagonist, suggesting that the SP effect was mediated by the enteric nervous system. In line with this it was shown that the SP-evoked release of VIP was also significantly diminished by hexamethonium. 3. Close I.A. infusions of methionine enkephalin (Met-enkephalin; 7-23 nmol min-1) or electrical stimulation of the sympathetic nerve fibres (6 Hz) to the intestine markedly diminished net fluid secretion and the release of VIP caused by SP given close I.A. 4. The cyclo-oxygenase inhibitor diclofenac (5 mg (kg body wt)-1, I.V.) or the histamine-1 receptor antagonist pyrilamine (10 mg (kg body wt)-1, I.V.) did not influence the fluid secretion caused by SP, indicating that the effects of SP were not due to the actions of prostaglandins or histamine. 5. It is proposed that SP activates a nervous reflex arch that we have shown to be activated by various luminal stimuli, including cholera toxin.(ABSTRACT TRUNCATED AT 250 WORDS)
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1157813Documentos Relacionados
- Intraluminal distension pressure on intestinal lymph flow, serosal transudation and fluid transport in the rat.
- Nervous release of vasoactive intestinal polypeptide from the feline uterus: pharmacological characteristics.
- Substance P provoked gamma-aminobutyric acid release from the myenteric plexus of the guinea-pig small intestine.
- Effects of feeding and lighting regimes on sugar transport in the rat small intestine.
- Vasoactive intestinal polypeptide and cholinergic mechanisms in cat nasal mucosa: studies on choline acetyltransferase and release of vasoactive intestinal polypeptide.