Ž . European Journal of Pharmacology 376 1999 223–232 www.elsevier.nlrlocaterejphar Cytokines induce increased endothelin ET receptor-mediated B contraction Erik Uddman ) , Sebastian Moller, Mikael Adner, Lars Edvinsson ¨ DiÕision of Experimental Vascular Research, Department of Internal Medicine, EB-blocket, 5 Õan, Lund UniÕersity Hospital, S-221 85 Lund, Sweden ˚ Received 10 May 1999; accepted 18 May 1999 Abstract The effect of cytokines on the induction of contractile endothelin ET receptors during organ culture was examined. Ring segments of B rat superior mesenteric artery were used fresh or incubated for 24 h in Dulbecco’s modified Eagle’s medium alone, or with either Ž . interleukin-1b, tumor necrosis factor-a TNF-a or interleukin-2. In fresh arterial segments there was no endothelin ET receptor-in- B duced contraction. After incubation, the selective endothelin ET receptor agonist sarafotoxin 6c evoked a contraction of 22 "6% B relative to that induced by 60 mM K q . The endothelin ET receptor-induced contraction was further increased to 125 "25% and B 157 "29% by interleukin-1b and TNF-a , respectively, while interleukin-2 did not alter the endothelin ET receptor-induced contraction. B The identity of the contractile receptor was confirmed as the endothelin ET receptor by the use of an additional specific endothelin ET B B receptor agonist, IRL 1620, and by antagonist experiments with FR 139317 and IRL 2500. The endothelin-1-induced contraction was not altered by either of the cytokines. Reverse transcriptase–polymerase chain reaction revealed increased levels of endothelin ET mRNA, B relative to endothelin ET mRNA following organ culture, suggesting that contractile endothelin ET receptors appear via de novo A B transcription. None of the cytokines changed the ratio of endothelin ET and endothelin ET receptor mRNA, indicating that the further A B increased sarafotoxin 6c-induced contraction is mediated through an enhancement of intracellular signalling mechanisms. q 1999 Elsevier Science B.V. All rights reserved. Ž . Keywords: Interleukin-1b; TNF-a tumor necrosis factor-a ; Interleukin-2; Endothelin-1; Sarafotoxin 6c; IRL 1620; Endothelin ET receptor B 1. Introduction Endothelin-1 is the most potent vasoconstrictor de- Ž . scribed to date Yanagisawa et al., 1998 . Its action in mammals is mediated through two distinct G-protein cou- Ž pled receptors: endothelin ET and ET receptors Arai et A B . al., 1990; Sakurai et al., 1990 . The endothelin ET recep- A tor is present in the smooth muscle cell layer, mediates vasoconstriction and may contribute to the maintenance of Ž . vascular tone Haynes and Webb, 1994 . The endothelin ET receptor was initially thought to be present exclu- B sively in the endothelium where it induces a transient reduction in vascular tone via release of nitric oxide or Ž . prostacyclin De Nucci et al., 1988; Lodge et al., 1995 . Lately, endothelin ET receptors have been shown to B ) Corresponding author. Tel.: q46-46-17-53-31; fax: q46-46-13-72- 77 mediate a contractile smooth muscle response in some vascular regions, mainly in low pressure systems such as Ž veins Bigaud and Pelton, 1992; Gardiner et al., 1994; . Lodge et al., 1995 . Plasticity of smooth muscle cells expressing endothelin ET receptors have been shown in B several pathological conditions: in healthy individuals, the subcutaneous and coronary arteries express contractile en- dothelin ET receptors but not contractile endothelin ET A B Ž . receptors Wenzel et al., 1994; Dagassan et al., 1996 . However, in the subcutaneous arteries of patients with coronary artery disease as well as in coronary arteries of patients with atherosclerosis, contractile endothelin ET B Ž receptors have been found Dagassan et al., 1996; Wenzel . et al., 1996 . In addition, upregulation of endothelin ET B receptors appear after experimental subarachnoid hemor- Ž . rhage Roux et al., 1995 . The phenomenon of inducible receptors as a response to pathological or altered physiological conditions has been described to be modulated by inflammatory mediators Ž . Hakonarson et al., 1996; Donaldsson et al., 1997 . Inter- 0014-2999r99r$ - see front matter q 1999 Elsevier Science B.V. All rights reserved. Ž . PII: S0014-2999 99 00381-7