Preliminary pharmacological characterization of the bovine isolated bronchial artery strip: a new preparation.

1 This paper describes a preliminary pharmacological study of the isolated helical strip of bovine bronchial artery under isotonic conditions in Krebs-Henseleit solution. 2 The tissue contracted to histamine and 5-hydroxytryptamine (5-HT), actions which were selectively antagonized by mepyramine and methysergide respectively. Histamine was not inhibited by metiamide and 5-HT was not affected by morphine. 3 Slow reacting substance of anaphylaxis (SRS-A), prostaglandin F2 alpha (PGF2 alpha) and PGE2 were spasmogenic, whereas PGE1 caused relaxation. No potential antagonists of these agents were tested. 4 Carbachol, at all concentrations, caused contractions of the bronchial artery which were completely, irreversibly blocked by atropine. 5 The spasmogenic action of phenylephrine was selectively blocked by dibenamine. Vessel strips which were partially contracted to histamine, relaxed to isoprenaline and salbutamol. The action of isoprenaline was inhibited similarly by either propranolol or practolol. The evidence therefore suggests the presence of functional alpha, beta 1 and beta 2-adrenoceptors.

Susceptibility of a rodent-adapted strain of Trypanosoma vivax to Berenil, Samorin and Novidium.

The susceptibility of a rodent-adapted strain of Trypanosoma vivax (Leeflant strain Y58) to Berenil, Samorin and Novidium was tested in mice. When infected mice were treated on the second day of detectable parasitaemia, there was complete cure with Berenil at 10 mg/kg, Novidium at 4 mg/kg and Samorin at 0.2 mg/kg body weight respectively. Berenil and Novodium at lower doses rendered the mice aparasitaemic for a few days followed by heavy parasitaemia (relapse) and death. Lower doses of Samorin, on the other hand, were curative for none or only some of the mice but without relapses. These observations are related to the accepted modes of action of these drugs and their use in the field.

Isometamidium concentrations in the sera of Boran cattle: correlation with prophylaxis against tsetse-transmitted Trypanosoma congolense.

Fifteen Boran cattle from a trypanosomiasis-free area were injected intramuscularly with isometamidium chloride at a dose of 1 mg/kg body weight. Thereafter, the cattle were challenged at monthly intervals with Glossina morsitans centralis infected with one of three populations of Trypanosoma congolense (IL 3893, IL 3889 or IL 1180) until all animals became infected. Isometamidium concentrations in the sera of these cattle were measured using a competitive enzyme-linked immunosorbent assay over the first 105 days following treatment. All cattle challenged with IL 3893 or IL 3889 developed infection following the first challenge, at which time the mean serum drug concentration in all treated cattle was 6 ng/ml. Cattle challenged with IL 1180 became infected following 6 to 8 monthly challenges. The mean serum drug concentration in these cattle at the time of their third monthly challenge with IL 1180 was 0.75 ng/ml. Trypanosome populations IL 3893 and IL 3889 were considered to be highly resistant to isometamidium, while IL 1180, relatively sensitive. It was therefore concluded that T. congolense persisting at serum isometamidium concentrations greater than 0.75 ng/ml can be considered moderately resistant, while those persisting at concentrations greater than 6 ng/ml can be considered markedly resistant. These results will be most valuable in the investigation of isometamidium resistance of T. congolense in the field.

Some considerations on veterinary drug use and supply in Nigeria.

There is widespread misuse of veterinary drugs in Nigeria resulting from controlled and unsupervised drug administration, underdosing and incomplete treatment. Development of resistance and toxicity are common consequences of this misuse. Drug shortage, uneven distribution, preponderance of fake and/or expired drugs and inadequate local drug production are some of the problems identified in veterinary drug supply. All these problems have an adverse effect on animal health and productivity and are related to an improperly coordinated veterinary service and the non-existence of national veterinary drug policy. Suggested solutions include rehabilitation and restructuring of the veterinary service, improved funding to support drug purchase, installation of self-servicing revolving funds, partial privatization, drug manufacture and appropriate legislations for veterinary drugs. These proposals are expected to overcome bottlenecks encountered in drug supply, distribution, delivery, prescription and use. Projections and plans must also be made toward the local development and manufacture of drugs for animal disease.

Toxic effects of glycerol in Swiss albino rats.

The acute toxicity of glycerol was studied in swiss albino rats. The median lethal dose (LD50) of glycerol in the local strain of swiss albino was determined to be 4.42 gm/kg body weight. Nervous signs were observed in the rats before death. Organ: body weight ratios of the heart, kidneys and liver were higher than normal, while those of the spleen and brain remained normal. No gross pathological lesion of these organs was observed. The histopathological lesions observed include congestion of blood vessels of the lungs and kidneys; accumulation of hemoglobin in renal tubules; renal tubular epithelial degeneration and desquamation; neuronal degeneration and necrosis, as well as occurrence of haemosiderin pigments.