dinoprost and detomidine

Twenty five Holstein-Friesian heifers, clinically normal and with regular oestrous cycles, were used for induction of superovulation (PMSG-PGF(2)alpha-Neutra-PMSG). Animals were divided into 5 groups receiving: I - detomidine (40 microg/kg b.w.), II - doxazosin (0.2 mg/kg b.w.), III - yohimbine HCL 1% (1 ml/50 kg b.w.), IV - carazolol (0.01 mg/ kg b.w., i.v.), and V - physiological saline (1 ml/50 kg b.w.). The heifers with PGF2 alpha-induced cycles were treated with the substances 88 hrs after being given a single i.m. injection of 2500 IU PMSG. All animals were examined by ultrasonography, and by the number and size of ovarian follicles > 3 mm in diameter. The follicles were divided into 3 groups according to the diameter. Blood plasma was stored at -20 degrees C until LH, P4, E2 and PGFM analyses. In the control (V) group, two waves of follicle growth were observed. Yohimbine produced a significant blockage of ovulation. The mean number of corpora lutea in the group III was significantly lower than that in the control group (p< 0.02). No significant differences in the number of corpora lutea were observed between the groups I, II and III. The increase in E2 concentrations could be the response to the PMSG treatment with two waves of growth of large follicles before and after ovulation. Pulsatile LH release was altered by yohimbinum injection, however, the greater amplitude of pulses immediately following yohimbinum administration are suggestive of a positive influence of the alpha-2 adrenergic receptors antagonist. Yohimbinum administration did not affect plasma concentration of examined hormones. There was a difference between the plasma levels of LH after the doxazosin injection. Single injection of the stimulators and blockers of adrenergic receptors did not affect superovulatory response in terms of the numbers of CL, unruptured follicles and embryos recovered. The affectivity of artificial insemination was not significantly different between the control group and the detomidinum groups, while in the yohimbinum group it was significantly lower.

Topics: Adrenergic alpha-Agonists; Adrenergic alpha-Antagonists; Adrenergic beta-Antagonists; Animals; Cattle; Dinoprost; Doxazosin; Estradiol; Estrus; Female; Gonadotropins, Equine; Imidazoles; Luteinizing Hormone; Ovarian Follicle; Progesterone; Propanolamines; Receptors, Adrenergic, alpha; Superovulation; Yohimbine

To investigate the vascular smooth muscle dysfunction of septic shock, in vitro isometric responses to phenylephrine (PE) and acetylcholine (ACh) were evaluated in aortic rings, with and without endothelium (+/-E), removed from male Wistar rats 1.5, 3 and 6 h after intravenous (i.v.) administration of 5 mg/ kg lipopolysaccharide (LPS) or vehicle. A reduction in maximum contraction (+/-E) and sensitivity (-E) to PE were identified at 6 but not at 1.5 or 3 h. Maximum relaxation to ACh (+E) was not affected by LPS treatment but sensitivity was increased at 1.5 and 3 h. Having identified 6 h as the time at which the most pronounced changes were observed, further studies at this interval found that maximum contraction to potassium chloride (+/-E), prostaglandin F2 alpha (+E) and detomidine (-E) and relaxation to salbutamol (-E) were less in aortic rings from endotoxaemic rats. Sensitivity to KCl (+/-E), PGF2 alpha (-E) and detomidine (-E) was also reduced. Relaxation to sodium nitroprusside and atrial natriuretic peptide was not changed. These results suggest that attenuated pressor responses to a variety of vasoactive agents may be expected in patients 6 h after systemic exposure to endotoxin and that this vasoplegia may influence the vascular side-effects of therapeutic agents.

Topics: Acetylcholine; Adrenergic alpha-Agonists; Adrenergic beta-Agonists; Albuterol; Analysis of Variance; Animals; Aorta, Thoracic; Atrial Natriuretic Factor; Dinoprost; Dose-Response Relationship, Drug; Endothelium, Vascular; Imidazoles; Injections, Intravenous; Isometric Contraction; Lipopolysaccharides; Male; Muscle Contraction; Muscle Relaxation; Muscle, Smooth, Vascular; Nitroprusside; Phenylephrine; Potassium Chloride; Rats; Rats, Wistar; Shock, Septic; Vasodilator Agents

The motor responses of the caecum and colon to stimulation of alpha 2-adrenoceptors by xylazine and detomidine at the recommended dose levels of 0.6 and 0.1 mg/kg were investigated in three ponies. The motor changes of the left ventral colon induced by continuous intra-arterial infusion of a prostaglandin (PGF2 alpha) were used to assess the relative inhibitory effects of xylazine and detomidine in a colic model. The administration of alpha 2-agonists inhibited the spiking activity on the whole of the large intestine for 20-30 min (xylazine) or 2-3 h (detomidine). However, the detomidine-induced inhibition was preceded by a short period of increased smooth muscle basal tone as indicated by strain-gauge force transducer measurements. This pattern of activity was neither reversed nor prevented by the administration of tolazoline (10 micrograms/kg/min) intra-arterially. In contrast, inhibition of the colonic phasic and tonic motor activity by alpha 2-adrenoceptor stimulation was reversed competitively by tolazoline. The intra-arterial infusion of prostaglandin F2 alpha (10 micrograms/kg/min) induced prolonged and sustained spiking activity that might be related to signs of mild colic. Detomidine, and to a lesser extent xylazine, relaxed the whole of the large intestine and this was accompanied by alleviation of the signs of visceral pain.

Topics: Adrenergic alpha-Agonists; Animals; Cecum; Colon; Dinoprost; Gastrointestinal Motility; Horses; Imidazoles; Prostaglandins F; Tolazoline; Xylazine