Preliminary studies of analgesic and anti-inflammatory properties of Opuntia dillenii aqueous extract.

Opuntia dillenii (Ker-Gawl) Haw is a cactus that belongs to the family Opuntiae. Lyophilized aqueous extract of the fruits of the plant, used in Canarian traditional medicine for gastrointestinal and bronchial troubles, was evaluated for analgesic and anti-inflammatory properties in rats and mice. The Opuntia dillenii extract (100-400 mg/kg, i.p.) inhibited, in a dose-related manner, carrageenan-induced paw edema in rats. A dose-dependent action was obtained against chemical (writhing test) and thermic (hot plate test) stimuli, respectively, with doses of 50 and 100 mg/kg.

Bradykinin B2-receptor-mediated positive chronotropic effect of bradykinin in isolated rat atria.

The positive chronotropic effect of bradykinin was investigated in isolated spontaneously beating atria of the rat. Cumulative additions of bradykinin (0.3-100 nM) caused a concentration-dependent increase in the beating rate of the atria by maximally 35+/-4 beats/min, approximately 25% of the 1 microM isoprenaline-induced maximal responses. In contrast, the active metabolite of bradykinin and selective bradykinin B1-receptor agonist, Des-Arg9-bradykinin, did not influence the spontaneous frequency of beating. Propranolol (1 microM) combined with prazosin (1 microM) did not affect the positive chronotropic effect of bradykinin. A selective bradykinin B2-receptor antagonist, Hoe 140, concentration-dependently shifted the response curves for bradykinin to the right, whereas the bradykinin B1-receptor antagonist, Lys-[Leu8]Des-Arg9-bradykinin had no effect. The tachycardic responses to bradykinin were potentiated by ramipril, an angiotensin-converting enzyme/kininase II inhibitor, but not affected by Nomega-nitro-L-arginine methyl ester hydrochloride, a nitric oxide synthesis inhibitor. Indomethacin and meclofenamate, two cyclooxygenase inhibitors, abolished the bradykinin-induced chronotropic effect. These results indicate that exogenous bradykinin induces a positive chronotropic effect that occurs independent of adrenoceptors. The bradykinin-induced chronotropic effect is mediated by bradykinin B2 receptors, whereas B1 receptors do not play a role in mediating this effect. Prostaglandins but not nitric oxide appear to be involved in bradykinin-induced positive chronotropic effect.

Positive chronotropic activity of bradykinin in the pithed normotensive rat.

The positive chronotropic effect of bradykinin was investigated in the pithed rat preparation. Cumulative treatment with bradykinin (0.20 nmol/kg-6.59 mumol/kg, intravenous [i.v.]) caused a dose-dependent increase in heart rate (HR) by a maximum of 80 +/- 3.3 beats min-1. In contrast, the active metabolite of bradykinin and selective bradykinin B1-receptor agonist, [des-Arg9]-bradykinin did not influence the spontaneous frequency of beating. Propranolol alone reduced the bradykinin-induced increase in HR and a combination of propranolol with prazosin abolished the chronotropic effect of bradykinin. The selective bradykinin B2 receptor antagonist. Hoe 140, dose-dependently shifted the dose-response curves of bradykinin to the right, whereas the bradykinin B1 receptor antagonist, des-Arg10-[Leu9]-kallidin proved ineffective. From our experiments it may be concluded that bradykinin induces tachycardia in the pithed rat primarily by stimulating the sympathetic ganglia leading to the release of noradrenaline, which subsequently activates cardiac beta 1-adrenoceptors. The bradykinin-induced chronotropic effect is mediated by bradykinin B2-receptors, whereas B1-receptors appear not to be involved.

Intertectal commissural projection in the lizard Gallotia stehlini: origin and midline topography.

The retinotectal projection of reptiles is largely crossed. The intertectal commissure is an important pathway that interconnects directly the two sides of the optic tectum. The rostrocaudal topography of intertectal commissural fibers at the dorsal midplane was examined by means of the in vitro horseradish peroxidase (HRP) labelling technique in the lizard Gallotia stehlini. Unilateral large deposits of tracer in the optic tectum as well as smaller deposits restricted to one quadrant were used to map the intertectal fibers anterogradely. Most commissural axons reached the contralateral side grouped into a dense bundle at the transition between two structurally distinct parts of the midbrain dorsal midline. The smaller rostral zone relates laterally to the griseum tectale, whereas the larger caudal zone relates to the tectum. The intertectal fibers seem to converge on the rostralmost part of the latter midline region, even though they originate throughout the optic tectum. A rough rostrocaudal tectotopic order was detected at the midline. Retrogradely labelled neurons were best obtained by depositing HRP directly within the compact commissure at the midline. These belong to pyriform cells in the periventricular layers 3 and 5. Axons labelled from the tectum did not enter the posterior commissure nor the intervening commissural region related to the griseum tectale.