Recent evidence suggests that catecholamines inhibit insulin release by stimulating alpha 2-adrenoreceptors in beta-cells of the pancreatic islets. In the present study, iv injections of 0.1 and 0.3 mg/kg of yohimbine, an alpha 2-adrenoreceptor antagonist, resulted in increased plasma insulin and decreased plasma glucose concentrations in the dog. The use of alpha 2-adrenoreceptor antagonists may be of value in non-insulin-dependent diabetic patients by counteracting the inhibitory influence of endogenous catecholamines.
SUMMARY Amitraz, a formamidine insecticide, is used topically in the treatment of demodicosis and other ectoparasitic infestations. When 3.78 L (containing 2.1 g) of amitraz (twice the recommended concentration) was applied to 5 dogs 4 hours before glucose (0.6 g/kg of body weight) was administered iv , plasma glucose concentration increased, but the increase in plasma insulin concentration, which usually follows iv administered glucose, was suppressed. The results suggested that amitraz induced hyperglycemia at least partly by inhibiting insulin release.
SUMMARY The effectiveness of 4-aminopyridine, doxapram, or yohimbine as antagonists against xylazine-induced cns depression in dogs was evaluated and compared, using the 2-way shuttle-avoidance paradigm. All drugs were given iv to 5 male dogs trained to avoid mild shock by jumping over a hurdle within 10 s after initiation of an audible tone. At dosages of 1 and 2 mg/kg of body weight, xylazine abolished or significantly decreased the mean number of avoidance responses and significantly increased the mean latency of avoidance responses. The analeptic 4-aminopyridine (0.5 mg/kg) did not significantly antagonize xylazine in all dogs. One dog convulsed both times it was given xylazine followed by 4-aminopyridine, but did not convulse when given either drug alone. Doxapram (5.5 mg/kg), a short-acting analeptic and respiratory stimulant, was only partially effective in antagonizing xylazine, and its antagonistic actions were brief. Yohimbine (0.1 mg/kg), an α 2 -adrenoreceptor-blocking agent, was superior to 4-aminopyridine and doxapram in its ability to antagonize xylazine-induced cns depression. Yohimbine consistently increased the mean number of avoidance responses to the maximum of 8 and consistently decreased the mean latency of avoidance responses to control values in dogs given 1 or 2 mg of xylazine/kg. In dogs given 2 mg of xylazine/kg, yohimbine was significantly more effective than 4-aminopyridine or doxapram in its ability to increase the mean number of avoidance responses and decrease the mean latency of avoidance responses. Results of the present study indicated that yohimbine was superior to 4-aminopyridine and doxapram in sustaining the reversal of xylazine-induced suppression of avoidance responses in dogs and that xylazine’s suppression of the avoidance responses may be mediated by α 2 -adrenoreceptors.
The optimal conditions for performing the caffeine CO2 breath test (CBT) were investigated in smokers and nonsmokers. Caffeine labeled with13C or 14C in all three (1, 3, and 7) methyl groups or specifically in the 1-, 3-, or 7-methyl groups were orally administered to healthy adults and the expiration of labeled CO2 was measured for 8 or 24 hr. The absolute rate of labeled CO2 excretion from trilabeled caffeine was proportional to the dose up to 3 mg/kg in all subjects. In smokers, the rate of labeled CO2 excretion averaged twice that in nonsmokers at all doses. A correlation was observed between the 2-hr cumulative CO2 excretion from trilabeled caffeine and the apparent oral metabolic clearance rate (MCR) of caffeine (r = 0.90). Monolabeled CBTs in smokers and nonsmokers demonstrated that 80% ± 4% of labeled CO2 expired in the breath during the first 2 hr of a trilabeled CBT was derived from the 3 position; at 6 to 8 hr equal amounts were derived from the 3 and 7 positions. Little N-demethylation was observed from the 1 position at any time during the 8-hr test. The results indicate that the 2-hr cumulative excretion of labeled CO2 could be used to accurately predict the metabolic clearance rate of caffeine and is the best CBT parameter for detecting the effect of smoking on caffeine N-demethylation. The data suggest that the primary routes of caffeine metabolism are 3-N-demethylation and ring hydroxylation and confirm that caffeine metabolites are N-demethylated primarily in the 3 and 7 positions. Clinical Pharmacology and Therapeutics (1982) 32, 261–269; doi:10.1038/clpt.1982.157
Two 1-hectare forest stands were chosen as sampling sites in the monitoring area of river Drava: one was a softwood willow-poplar (Salici-Populetum) gallery forest directly along the river in the neighbourhood of Vízvár, whereas the other was a lowland alder gallery forest (Paridi quadrifoliae-Alnetum) within the Lankóci forest. Quadrate sampling method and line transect (the latter in Vízvár in 2001) were applied. The number of the box-type live traps was 121 in the grid, and a maximum of 120 in the transect. Trapping was done using the capture-mark-recapture (CMR) method. So far 3 shrew and 3 rodent species have been indicated in the Vízvár sample area, and 8 species comprising 5 rodents and 3 shrews in the Lankóci forest stand. The dominant species in the willow-poplar gallery forest has been Apodemus agrárius (Pallas, 1771), whereas the abundant characteristic species of the alder forest has been Clethrionomys glareolus (Schreber, 1780).
At the upper region of Drava 408 pellets were collected from 14 sample sites in autumn 2000 and
1975 small mammal individuals were identified during analyses. Among the Insectivora, six shrew species
belonging to the family Soricidae were identified, whereas among the rodents (Rodentia) 12 species were differentiated plus one genus-level (Apodemus spp.) identification was made. Based on the sample, pellets were
arranged into three groups: 1. Vizvar area, 2. Berzence area, 3. Gyekenyes area, which enabled a comparative
analyses of the three separate area-units along the upper region of Drava, among which the most diverse small
mammal community was in the Gyekenyes area.
