ag-213 and 1-6-bis(cyclohexyloximinocarbonyl)hexane

We have evaluated the signal transduction pathways whereby, in comparison with epidermal growth factor-urogastrone, ethanol causes a rapid contractile response in guinea pig gastric longitudinal muscle. As for epidermal growth factor (EGF), the ethanol-induced contraction required extracellular calcium, was sensitive to the tyrosine kinase inhibitors genistein and tyrphostin 47 (AG213), and was blocked by both the cyclo-oxygenase inhibitor, indomethacin, and the diacylglycerol lipase inhibitor, U57908. The 50% effective concentration (EC50) for the contractile action of ethanol (approximately 140 mM) was lower than that for propanol and methanol and was not affected by the aldehyde dehydrogenase inhibitor, 4-methyl pyrazole. The actions of ethanol were distinct from those of EGF in that EGF-induced contractions were sensitive to the kinase C inhibitor GF109203X, and the EGF receptor kinase inhibitor PD153035, whereas ethanol-induced contractions were refractory to these inhibitors. Further, EGF-induced contractions were attenuated by the voltage-sensitive calcium channel antagonist, nifedipine, whereas the ethanol-induced contractile response was resistant to nifedipine but blocked by the "receptor-operated" calcium channel antagonist SKF96365. We conclude that ethanol without metabolism via alcohol dehydrogenase causes a contractile response in gastric longitudinal muscle tissue via a tyrosine kinase inhibitor-sensitive signal pathway that is parallel in many respects but yet is distinct from that activated by EGF.

Topics: 1-Propanol; Animals; Calcium; Catechols; Cyclohexanones; Enzyme Inhibitors; Epidermal Growth Factor; Ethanol; Fomepizole; Genistein; Guinea Pigs; Humans; In Vitro Techniques; Indoles; Indomethacin; Isoflavones; Male; Maleimides; Methanol; Muscle Contraction; Muscle, Smooth; Nitriles; Protein-Tyrosine Kinases; Pyrazoles; Quinazolines; Signal Transduction; Stomach; Tyrphostins

In guinea pig gastric longitudinal (LM) and circular (CM) muscle strips, angiotensin-II (Ang-II) caused a concentration-dependent contraction that required extracellular calcium and that could not be attributed to the secondary release of agonists from neural elements. Contractions in both the LM and CM were blocked by the Ang-II AT1 receptor antagonist, Losartan (DuP 753, pA2 9.1) but not by the AT2 antagonist, PD 123319. However, in the LM preparation, indomethacin (3 microM) blocked Ang-II-mediated contraction, whereas in the CM contraction was resistant to indomethacin. Contractions caused by Ang-II in the CM preparations were also unaffected by inhibitors of leukotriene biosynthesis, but were partially (58%) inhibited by the cytochrome P450 monooxygenase inhibitor, ketoconazole. The diacylglycerol lipase inhibitor, U57,908, at a concentration (20 microM) that completely blocked the contractile action of epidermal growth factor in the LM, caused a substantial inhibition of Ang-II-mediated contraction in both the LM (55% inhibition) and CM (75% inhibition). The phospholipase A2 inhibitor, mepacrine caused a modest inhibition (24%) of contraction in both preparations. In the presence of U57,908, mepacrine further inhibited contraction caused by Ang-II in the LM preparation. The tyrosine kinase (YK) inhibitors, genistein and tyrphostin (RG 50864) selectively and completely blocked Ang-II-mediated contraction in the LM, without affecting contractions caused by carbachol and bradykinin. In the CM preparation, the two YK inhibitors were selective, but only partially (40-60%) blocked Ang-II-mediated contraction, without affecting contractions caused by bradykinin and carbachol.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Angiotensin II; Animals; Biphenyl Compounds; Calcium; Catechols; Cyclohexanones; Dose-Response Relationship, Drug; Epidermal Growth Factor; Genistein; Guinea Pigs; Imidazoles; In Vitro Techniques; Indoles; Indomethacin; Isoflavones; Losartan; Male; Muscle, Smooth; Nitriles; Protein-Tyrosine Kinases; Pyridines; Quinacrine; Signal Transduction; Stomach; Tetrazoles; Tyrphostins