Response of rat jejunum to angiotensin II: role of norepinephrine and prostaglandins.
At low doses, angiotensin II (AII) stimulates jejunal sodium and water absorption in the pentobarbital sodium-anesthetized rat. This response to the hormone can be blocked by cycloheximide and has a rapid onset and decay, indicating that any protein involved must have a short half-life and/or fast turnover. At high doses, AII inhibits jejunal absorption by a process that does not involve protein synthesis and has a rapid onset but slow decay. The AII-induced inhibition of water absorption can be abolished, and a net stimulation ensues after pretreatment of the animals with meclofenamate or indomethacin, suggesting that at high doses AII stimulates intestinal prostaglandin biosynthesis. The AII analogue, [Sar1,Leu8]AII, significantly stimulated jejunal water absorption and was devoid of any inhibitory response at any dose administered. Simultaneous infusion of low doses of [Sar1,Leu8]AII and AII resulted in a stimulation of water transport, while simultaneous infusion of high dose [Sar1,Leu8]AII and AII also stimulated water absorption. It is suggested that the AII analogue is a full agonist with regard to stimulation of jejunal transfer but antagonizes the inhibitory response to high doses of AII. A model consistent with these data is discussed.
D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D004305:Dose-Response Relationship, Drug; D007213:Indomethacin / Q000494:pharmacology; D007408:Intestinal Absorption / Q000187:drug effects; D007583:Jejunum / Q000187:drug effects*; D008297:Male; D008469:Meclofenamic Acid / Q000494:pharmacology; D009638:Norepinephrine / Q000502:physiology*; D011453:Prostaglandins / Q000502:physiology*; D014176:Protein Biosynthesis; D051381:Rats
D011453:Prostaglandins; D000804:Angiotensin II; D008469:Meclofenamic Acid; D009638:Norepinephrine; D007213:Indomethacin