Endothelium-dependent vasorelaxing activity of aqueous extracts of Ilex paraguariensis on mesenteric arterial bed of rats.

The effects of aqueous extracts of Ilex paraguariensis leaves (AEIp) were studied. Mesenteric arterial bed (MAB), precontracted by methoxamine with or without intact endothelium, was mounted on a tissue bath and exposed to plant extracts (bolus). The bolus injections of AEIp (300-1050 microg) significantly inhibited, in a concentration-dependent manner, the maximal contractile response induced by methoxamine (30 microm) in MAB. The endothelium-dependent relaxations were reversed by N(G)-nitro-L-arginine methyl ester (10 mM), whereas methylene blue (100 microM) was not capable of effectively inhibiting the AEIp-induced vasodilatation of MAB. The vasorelaxing effect of AEIp persisted in the presence of indomethacin (10 microM). These results suggest the involvement of NO of endothelial source (or others factors) in this vasodilatory effect.

Paradoxical increases of circulating nonesterified fatty acids in somatotropin treated cattle undergoing mild disturbances.

Effects of various doses of bovine somatotropin (bST) on plasma concentrations of nonesterified fatty acids (NEFA) were studied in a 14-d Latin square with six Holstein heifers. Animals were given daily injections of excipient or bST at 12:00 p.m. and fed twice daily at 7:00 a.m. and 7:00 p.m. On Day 14, plasma NEFA remained low through the day except around the 7:00 p.m. feeding when they were substantially elevated. The elevation was significantly greater in bST-treated animals and corresponded to the excitement of the animals in anticipation of the evening feeding. To further investigate this phenomenon, a second experiment was conducted in which nine growing Holstein steers were fed hourly and received either daily intramuscular (i.m.) injection of excipient or bST (120 mg/kg BW) for 15 d in a crossover design. Daily profiles of NEFA were obtained under undisturbed conditions or concurrently with intensive handling. Although no elevations could be detected in any case in control animals, bST caused a substantial rise in NEFA concentration only when animals were subjected to intensive handling. This suggested that NEFA peaks noted in bST-treated heifers in the first experiment resulted from increased ability of adipose tissue to respond to adrenergic stimulation associated with the anticipation of feeding. Consistent with this hypothesis, plasma NEFA concentrations in bST-treated steers were increased to a greater extent during a challenge involving i.v. injection of epinephrine. This amplification of adipose tissue response by bST must be considered when conducting intensive studies. Even the minimal excitement associated with blood sampling can confound the results regarding lipid mobilization, and this may have contributed to the notion that ST is a lipolytic hormone.

Signs, larval burdens, and serological responses of dogs experimentally infected with Trichinella spiralis Owen, 1835.

The effects of infections of Trichinella spiralis on 10 specific-pathogen-free Beagles were examined. Eight puppies received either 100, 500, 1,000, or 5,000 larvae, and 2 adult dogs received 1,000 larvae. Blood was drawn every 4 days, beginning 5 days before infection, for the determination of relative eosinophil numbers. Creatine kinase levels were monitored before infection, two weeks after infection, and one month after infection. The dogs were euthanized 1 month postinfection, and larvae were counted in muscle digests of 10 gram samples of diaphragm, pectoralis superficialis, masseter, biceps brachii, and vastus lateralis. The dogs displayed minor signs of gastrointestinal upset during the first week after infection. The dogs also developed a slight eosinophilia with a magnitude that was dependent on the number of larvae the dog received. All infected dogs, but one that had received 500 larvae, had a positive reaction with larval excretory-secretory products of T. spiralis; adult dogs had the greatest immunologic response. The creatine kinase levels were found not to be related to either the time postinfection or the magnitude of the larval dose. The number of larvae recovered from the muscles (maximum of 70 per gram) was dependent on the dosage of larvae received, but there was no significant predilection of the larvae for any of the five examined muscle groups.