dinoprost and 8-phenyltheophylline

In electrically driven myocardial preparations obtained from chronically methylxanthine-[aminophylline (APH) and 8-phenyltheophylline (8-PT)] or solvent(DMSO)-treated guinea pigs no differences were found in alteration of mechanical activity under hypoxia and reoxygenation. The vasoconstrictor effects observed after in vitro exposure of pulmonary arterial preparations (excised from either methylxanthine- or solvent-treated guinea pigs) to both noradrenaline and PGF2 alpha were also similar. In methylxanthine-treated vascular tissues, however, nitroglycerin and NO exerted more pronounced vasorelaxant effect than in specimens prepared from solvent-treated guinea pigs.

Topics: Aminophylline; Animals; Atrial Function; Cardiotonic Agents; Dinoprost; Female; Guinea Pigs; Hypoxia; In Vitro Techniques; Muscle, Smooth, Vascular; Nitric Oxide; Norepinephrine; Pulmonary Artery; Purinergic P1 Receptor Antagonists; Theophylline; Time Factors; Vasoconstriction

Rat liver Ito cells were cultured for 24 hr with 20% newborn calf serum. Stimulation with the sympathetic neurotransmitter noradrenaline (0.1 mumol/L to 1 mmol/L) led to a dose-dependent increase in prostaglandin F2 alpha release and a slightly smaller enhancement of prostaglandin D2 production. Prostaglandin F2 alpha and prostaglandin D2 synthesis was highest in the first 30 sec after stimulation. Stimulation with the possible cotransmitter ATP (10 mumol/L and 1 mmol/L ATP) also enhanced both prostaglandin F2 alpha and prostaglandin D2 release strongly. The release was highest again during the first 30 sec. Stimulation with noradrenaline and ATP simultaneously did not increase the effects of noradrenaline or ATP alone. Adenosine had no effect on prostaglandin production. The effects of noradrenaline were inhibited specifically by the alpha 1-adrenoreceptor antagonist prazosin but not by the p1-purinoreceptor antagonist 8-phenyltheophylline. The effects of ATP were not antagonized by the inhibitors. Because the metabolic actions of sympathetic hepatic nerves can be inhibited by inhibitors of prostanoid synthesis and mimicked by prostaglandins F2 alpha and D2, and because the Ito cells are well innervated, our results permit the conclusion that Ito cells could be involved in the nervous signal chain: During sympathetic nerve action the neurotransmitter noradrenaline and the cotransmitter ATP cause increases in prostaglandin F2 alpha and prostaglandin D2 release from Ito cells within 30 to 60 sec by way of alpha 1 and p2 receptors, respectively. The released prostaglandins then activate glycogenolysis in the hepatocytes proper.

Topics: Adenosine; Adenosine Triphosphate; Animals; Cells, Cultured; Dinoprost; Endothelium; Kupffer Cells; Liver; Male; Norepinephrine; Prazosin; Prostaglandin D2; Rats; Rats, Wistar; Receptors, Adrenergic, alpha-1; Receptors, Purinergic P2; Stimulation, Chemical; Theophylline

The effect of intravenously administered prostaglandin F2 alpha on gastric acid secretion was investigated in anaesthetized rats. Doses of 0.03-0.3 mg/kg PGF2 alpha stimulated gastric acid output in rats with intact vagi, whereas an inhibitory effect was observed in vagotomized animals. Treatment with 5 mg/kg of Na-meclofenamate intravenously attenuated the secretory response to PGF2 alpha, while 10 mg/kg of indomethacin intravenously and 3 mg/kg of 8-phenyltheophylline intraperitoneally were without any effect. The results indicate that intravenously administered PGF2 alpha stimulates gastric acid secretion in anaesthetized rats via activation of the vagus nerve. The effects of Na-meclofenamate and indomethacin suggest that PGF2 alpha may exert its secretagogue action via specific receptors. The lack of the effect of 8-phenyltheophylline indicates that adenosine which reportedly had a similar effect on gastric secretion after intravenous injection seems not to be involved here.

Topics: Animals; Dinoprost; Dose-Response Relationship, Drug; Gastric Acid; Indomethacin; Male; Meclofenamic Acid; Rats; Rats, Inbred Strains; Stimulation, Chemical; Theophylline; Vagotomy

The aim of this study was to test the effect of adenosine and four of its analogues, 5'-(N-ethyl)carboxamidoadenosine (NECA), 2-chloroadenosine (2-CADO), L-phenylisopropyladenosine (L-PIA), and N6-cyclohexyl-adenosine (CHA), on prostaglandin (PG) F2 alpha-constricted pig basilar arteries, and from their rank order of potency determine the receptor type involved. The order of potency for the relaxation of the PGF2 alpha constriction was NECA greater than adenosine, 2-CADO greater than L-PIA greater than CHA, which is in keeping with the A2 receptor subtype. The study also investigated the effects of a known adenosine antagonist, namely, the xanthine derivative 8-phenyltheophylline, which at concentrations having no intrinsic effect (10(-8) and 10(-7) M) produced a significant shift to the right only for the NECA dose-response curve.

Topics: 2-Chloroadenosine; Adenosine; Adenosine-5'-(N-ethylcarboxamide); Animals; Basilar Artery; Dinoprost; Dose-Response Relationship, Drug; Phenylisopropyladenosine; Prostaglandins F; Receptors, Purinergic; Swine; Theophylline; Vasodilation; Vasodilator Agents