摘要:

SUMMARYNonadrenergic, noncholinergic (NANC) innervation, the third division of the autonomic nervous system, has both inhibitory and excitatory parts. The excitatory part received only limited attention. Substance P has been suggested to be the neurotransmitter of the excitatory part. The NANC‐inhibitory innervation has recently been studied in detail. Although the neurotransmitter has not been conclusively identified, a substantial body of evidence exists to support vasoactive intestinal peptide (VIP) as the neurotransmitter. VIP is widely distributed in the body. Reports show that this innervation in animals and man plays a significant role in both health and disease. Pathological conditions could result from either an increase or decrease in VIP production. An absence of VIP‐producing neurons has been identified to be responsible for Hirschsprung's disease in the alimentary system and hyperactive airways in the respiratory system. An increase in VIP production is associated with chronic water diarrhea syndrome in humans. Taking these factors into consideration, various therapeutic measures are suggested with the use of VIP or its antagoni

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1989.tb00652.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The disposition and absorption kinetics of gentamicin were studied in healthy, mature male and female turkeys (n= 10). Single doses of gentamicin (5 mg/kg) were injected either i.v. or i.m. with a 30‐day rest period between each treatment. Baseline and serial venous blood samples (n = 17) were collected from each turkey. Serum concentrations of gentamicin were determined in duplicate for 24 h after each treatment, using radio‐immunoassay. Using nonlinear least‐square regression methods, the combined data of the i.v. and i.m. treatments were best described by a two‐compartment open model. Kinetic analysis of the data after a single i.v. dose provided the following mean values:tl/2α= 0.170 ± 0.093 h,tl/2α= 2.57 ± 0.79 h,MRT= 3.62 ± 0.96 h,Vc= 0.090 ± 0.017 l/kg,Vd(ss)= 0.172 ± 0.024 l/kg,Vd(area)= 0190 ± 0.030 l/kg. andClt= 49.8 ± 9.8 ml/h/kg. After a single i.m. dose, the following mean values were determined:MRT= 5.10 ± 1.73 h,t1/2 abs= 0.74 ± 0.66 h,ttag= 0.07 ± 0.19 h,Cl±/F = 50.7 ± 12.5 ml/h/kg,Vd(area/F= 0.193 ± 0.044 l/kg, andF= 102 ± 21%. Kinetic calculations made with the single i.m. data predicted that an i.m. injection of gentamicin at the dosage rate of 3 mg/kg q. every 12 h would provide average steady state serum conce

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1989.tb00653.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Theophylline was administered in a three‐way crossover design study to six cats intravenously (Aminophylline USP, Invenex Laboratories, Chagrin Falls, OH) and orally as two sustained‐release formulations (Slo‐bid Gyrocaps® (SB), William H. Rorer, Inc., Fort Washington, PA; Theo‐Dur® Tablets (TD), Key Pharmaceuticals, Miami, FL). Values were determined for mean residence time (SB = 19.4 ± 3.2 h; TD = 15.8 ± 4.8 h), mean absorption time (SB = 8.0 ± 2.3 h; TD = 4.8 ± 2.3 h), absolute bioavailability (SB = 82 ± 27%; TD = 76 ± 38%), and time to peak plasma concentrations (SB = 8 h; TD = 8 h). After normalization to a dose of 25 mg/kg, the average peak plasma concentrations were also predicted (SB = 10.5 ± 3.4 μg/ml; TD = 14.3 ± 6.7 μg/ml). Slo‐bid® was predicted to provide the least peak: trough fluctuation in theophylline concentrations. Slo‐bid® and Theo‐Dur® appear to have pharmacokinetic characteristics which, if given once‐daily, would maintain plasma theophylline concentra

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1989.tb00654.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Plasma ampicillin concentrations were determined in a cross‐over trial involving five cows after single intramuscular or intra‐abdominal administration of sodium ampicillin (10 mg/kg) and ampicillin anhydrate (40 mg/kg). After injection of sodium‐ampicillin, high plasma concentrations were reached within 10 min; Cmaxfollowing intramuscular injection was 9.1 μg/ml and after intraabdominal injection 7.5 μg/ml. Urine concentrations of ampicillin were low after 24 h (1–1.5 μg/ml). No significant changes in blood leucocyte numbers, plasma zinc, iron or fibrinogen levels occurred. After injection of ampicillin anhydrate 1 h elapsed before maximum plasma levels were obtained; Cmax was 5.4 μg/ml after intramuscular and 6.7 μg/ml after intra‐abdominal administration. Urine concentrations were very high (238–303 μg/ml) after 24 h and stayed above 1 (μg/ml for 6 days. After administration of ampicillin anhydrate a significant increase in blood neutrophils (P<0.01) and a significant increase in plasma fibrinogen was measured after intramuscular and intra‐abdominal injection (P<0.05). A significant decrease in plasma zinc concentration after intra‐abdominal injection occurred (P<0.05). In abdominal surgery in cows in which contamination cannot be prevented, and practical objections inhibit preoperative administration, intramuscular or intra‐abdominal administration during surgery of sodium ampicillin seems justified. Ampicillin anhydrate should not b

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1989.tb00655.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

In dwarf goats fasted for 2 h, i.v. administration of the benzodiazepine (BZ) agonists diazepam (60 μg/kg), brotizolam (2 and 4 μg/kg) and climazolam (100 μg/kg) induced hyperphagic effects, whereas i.v. injections of the BZ‐antagonist flumazenil (R°15–1788; 0.5 mg/kg), the anthelmintic ivermectin (0.1 mg/kg), the 5‐HT2 antagonist ritanserine (0.1 mg/kg), ACTH (10 μg/kg) and prednisolone (1 mg/kg) were inactive in a 30‐min feeding test. Both the BZ‐antagonist R°15–3505 (≤ 0.1 mg/kg) and the opiate receptor antagonist naloxone (0.1 mg/kg) had anorectic effects in dwarf goats given 30 min access to a palatable pelleted concentrate. The hyperphagic effects of climazolam and brotizolam were not antagonized by flumazenil, whereas similar doses of this drug completely reversed muscle incoordination and ataxia induced by much higher doses of these BZ‐agonists. In the combination experiments with naloxone and BZ‐agonists, naloxone antagonized the hyperphagic effects of both diazepam and brotizolam. Similarly, in the diazepam–R°15–3505 study, there was a significant effect of diazepam and a significant inhibition of this effect by R° 15–3505 (50 μg/kg). In the diazepam–ivermectin combination experiment no evidence for drug potentiation was found. These results and the mode of action of the above mentioned drugs are discusse

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1989.tb00656.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Grondel, J.L., Nouws, J.F.M., Schutte, A.R.&Driessens, F. Comparative pharmacokinetics of oxytetracycline in rainbow trout(Salmo gairdneri)and African catfish(Clarias gariepinus). J. vet. Pharmacol. Therap.12, 157–162.A comparative pharmacokinetic study was conducted in rainbow trout(Salmo gairdneri)and African catfish(Clarias gariepinus)following intravenous (i.v.) and intramuscular (i.m.) administration of oxytetracycline (OTC) at a dose rate of 60 mg/kg body weight. Trout and catfish were kept in aerated tap water in tanks at constant temperatures of 12°C and 25°C, respectively. The two‐ and three‐compartment open models adequately described plasma drug disposition in African catfish and rainbow trout respectively, following i.v. OTC administration. Compared to catfish (Cop= 86 ± 10 μg/ml) an eightfold higher extrapolated zero time concentration was obtained in trout (Cop= 753 ± 290 μg/ ml). A significant difference was observed with respect to the relatively large apparent distribution volumes (Vd(area)) after i.v. OTC administration (trout, mean value: 2.1 l/kg; catfish, mean value: 1.3 l/kg). The mean final elimination half‐lives of both fish species were greater than previously reported in mammals (trout, 89.5 h; catfish, 80.3 h). A mean maximum plasma concentration (Cmax = 56.9 μg/ml) was obtained in trout at 4 h after i.m. administration of OTC. In catfish a lower Cmaxof 43.4 (μg/ml was determined at about 7 h. No significant difference was observed with respect to bioavailability following i.m. administration of OTC (trout, 85%

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1989.tb00657.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Daily subcutaneous BST injection in lactating cows, bulls and castrated male dwarf goats did not induce significant changes in the pharmacokinetic parameters of antipyrine (AP) and sulphadimidine (SDD). Similarly, no changes were obtained after injection of slow‐release BST formulations in lactating cows and non‐lactating female goats. In contrast to androgenic hormones, both zeranol and proligestone had no effect upon the disposition of AP and SDD, although both synthetic hormones did induce enhanced plasma somatotropin concentrations. In goats, metabolic effects induced by zeranol and BST included significant reductions in plasma urea values, whereas plasma creatinine levels were somewhat lower after daily BST administrat

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1989.tb00658.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The effects of the β2‐agonist salbutamol, on pig heart rate and blood pressure were evaluated at the expected commercially used concentration of 3 ppm in final feed, and at three times this level. Salbutamol was administered to pigs previously fed on control diet (‘naive’), and in a second study to pigs fed 3 ppm salbutamol for 19 days (‘acclimatized’). Heart rate and blood pressure were measured in conscious 30 kg pigs before (pre‐ingestive), during (ingestive) and after ingestion (absorptive) of feed containing 3 or 9 ppm salbutamol. To assess any interaction with ‘stress genotype’ pigs, measurements were performed in Large White and Pietrain‐cross breeds. The mean preingestive heart rates for the Large White and Pietrain‐cross pigs were 127 and 109 beats/min, respectively. The corresponding figures for mean arterial blood pressure were 121 and 122 mmHg. The act of ingesting control feed caused heart rate to rise by 36–39% and blood pressure to increase by 17–27%. During the absorptive phase for ‘naive’ pigs fed 3 ppm salbutamol in the diet, blood pressure fell 5–11% and heart rate increased 20–24%, reflecting a classical baroreceptor mediated response. At 9 ppm the fall in blood pressure of 5–11% was similar to that at 3 ppm, while the rise in heart rate was larger at 31–38%. The magnitude of the changes at both 3 and 9 ppm was less than that evoked by the act of ingestion, with the exception of the heart rate response in Large Whites at 9 ppm, which was similar. The responses of the two breeds were comparable, indicating that salbutamol is unlikely to exacerbate the cardiovascular responses seen in potentially stress‐susceptible pigs. The acute changes elicited by 3 ppm salbutamol during the absorptive phase in ‘naive’ pigs were abolished or substantially less in acclimatized pigs, implying a tachyphylaxis to the agonist's actions. This was confirmed by 9 ppm of salbutamol increasing heart rate of ‘acclimatized’ Large Whites to the same degree as 3 ppm in ‘naive’ counterparts. The desensitization in Pietrain‐cross pigs was even more marked with no increase in heart rate produced by 9 ppm salbutamol following acclimatization. These data, combined with the rapid tachyphylaxis of response, indicate that salbutamol at the intended commercial inclusion of 3 ppm will not compromise the

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1989.tb00659.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The pharmacokinetics of theophylline at rest and the effects on cardiorespiratory and blood lactate responses to exercise were investigated after repeated oral administrations in six healthy Standardbred horses. A dose of 5 mg/kg body weight was administered every 12 h. The binding of theophylline to plasma protein was also determined. There was good agreement between predicted and observed plasma concentrations of theophylline at steady state. The mean half‐life of elimination was shown to be 17.0 ± 2.5 h, the mean half life of absorption was 1.6 ± 1.8 h, the apparant volume of distribution was 852 ± 99.0 ml/kg and total plasma clearance 0.61 ± 0.08 ml/kg/min. Theophylline showed very low plasma protein binding (12%). The heart rate and blood lactate levels, during and after exercise, were significantly increased during theophylline‐treatment. There was an increase of the arterial oxygen tension after exercise and the arterial carbon dioxide values before and after exercise were significantly lower than the premedication values. No severe adverse effects of the drug were noted. The recommended oral dose is therefore 5 mg/kg every 12 h but due to inter‐individual variation, an adjustment of the dose may be necessary. The changes in the studied exercise parameters indicate that the performance capacity may be impaired by theophylline in the heal

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1989.tb00660.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The effects of single i.v. and p.o. doses (5 mg/kg) of fenbendazole were evaluated on thyroxine, tri‐iodothyronine, corticosterone, hematology, clinical chemistries, and serum proteins in 10 white Pekin ducks. Fenbendazole was administered i.v. (n= 5) as a 3% dimethyl sulfoxide solution and p.o. (n= 5) as a 10% commercial suspension. Serum enzyme concentrations, total protein and protein fractions, glucose, cholesterol, uric acid, sodium, and potassium were unchanged from baseline values. Serum triglycerides decreased consistently in the i.v.‐treated group but remained unchanged in the p.o.‐treated group. Serum chloride was consistently elevated above baseline values for both i.v.‐ and p.o.‐treated ducks, while inorganic phosphate was consistently decreased only in the i.v.‐treated group. Hemoglobin and hematocrit values generally were below baseline values. Leukocyte values varied considerably and were not significantly different from baseline values. Serum thyroxine and tri‐iodothyronine values in both the i.v.‐ and p.o.‐treated groups were not changed significantly from baseline values. Serum corticosterone values were not changed in the i.v.‐treated groups but they were decreased at various times in the p.o.‐treated group. Although there were some sporadic significant changes in the parameters measured versus baseline values all values remained within the physiologic limits for ducks. The safety of fenbendazole has been previously demonstrate

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1989.tb00661.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY