PubMed Health⌕ Search

Biomedical subjects

R C Hatch

Publications and source records attributed to R C Hatch.

At least 37 records · Page 2Linked to original sources
PubMed1986

Effect of clonidine, quipazine, and LY 53857 on the prolactin-suppressant action of bromocriptine in rats.

The alpha 2-adrenergic agonist clonidine hydrochloride, the serotonin agonist quipazine maleate, and the serotonin (5-HT2) antagonist LY 53857 were tested alone and in various combinations for their capabilities to increase mean serum prolactin (MSP) concentrations in rats given the synthetic ergot alkaloid CB-154 (2-bromo-alpha-ergocriptine), a known prolactin suppressor. The LY 53857 and the combination of clonidine, quipazine, and LY 53857 significantly decreased MSP concentrations. Quipazine given alone (10 mg/kg of body weight) was best able to increase MSP concentration and has potential to antagonize prolactin-depressant effects of ergot alkaloids.

Animals↗
PubMed1985

Antagonism of xylazine sedation with yohimbine, 4-aminopyridine, and doxapram in dogs.

Groups of atropinized dogs (6 dogs/group) were sedated with xylazine (2.2 mg/kg of body weight, IM). At recumbency, the dogs were given IV saline solution (control groups), yohimbine (0.05, 0.1, and 0.2 mg/kg), 4-aminopyridine (4-AP; 0.3, 0.6, and 0.9 mg/kg), doxapram (0.5, 1.0, 2.0, and 4.0 mg/kg), or the smallest dose of these antagonists in dual combinations or in triple combination. Two additional groups were sedated with an overdose of xylazine (11 mg/kg, IM). At recumbency, 1 of these groups was given saline solution IV and the other group was given yohimbine IV (0.4 mg/kg) as the antagonist. With the 2.2 mg/kg dose of xylazine, control mean arousal time (MAT) and mean walk time (MWT) were 15.5 minutes and 24.8 minutes, respectively. These values were decreased by the individual antagonists to 0.5 to 2.5 minutes and 0.9 to 7.4 minutes, respectively. Approximate equipotent doses of antagonists (mg/kg) were: yohimbine, 0.2; 4-AP, 0.6; and doxapram, 0.5. Relapses did not occur after yohimbine or 4-AP. With doxapram, muscle tremors and spasms, abnormal postures, or aggressive behavior occurred in several dogs and several dogs had partial or complete relapses. The small doses of individual antagonists were synergistic with regard to MAT, MWT, and duration of residual sedation, but the various combinations of antagonists were not more effective in these regards than were larger doses of the single antagonists. With the overdose of xylazine, control MAT and MWT were 41.5 minutes and 144.5 minutes, respectively. Yohimbine decreased these values to 2.2 minutes and 2.5 minutes, respectively. Relapses did not occur.(ABSTRACT TRUNCATED AT 250 WORDS)

4-Aminopyridine↗
PubMed1985

Reversal of thiopental-induced anesthesia by 4-aminopyridine, yohimbine, and doxapram in dogs pretreated with xylazine or acepromazine.

Groups of atropinized dogs (6 dogs/group) were sedated, using xylazine HCl (2.2 mg/kg of body weight, IM) or acepromazine maleate (0.25 mg/kg, IM), and were anesthetized to loss of pedal reflexes, using thiopental, IV. The dogs were given 1 of the following test antagonists, IV: saline solution (2 ml; control group), 4-aminopyridine (4-AP; 0.5 mg/kg), yohimbine (0.4 mg/kg), doxapram (5.0 mg/kg), or dual combinations of the latter 3 substances in the same doses as used for each agent. In xylazine-treated dogs, the mean dosage of thiopental required to induce anesthesia was 4.8 mg/kg. Control mean arousal time (MAT) and walk time (MWT) were 37.1 minutes and 53.8 minutes, respectively. These values were decreased to less than 2 minutes and less than 3 minutes, respectively, by yohimbine, 4-AP + yohimbine, and doxapram + yohimbine. With doxapram and with 4-AP + doxapram, MAT was less than 2 minutes and MWT was less than 8 minutes. In acepromazine-treated dogs, the mean dosage of thiopental required for anesthesia was 15.0 mg/kg. Control MAT and MWT were 20.7 minutes and 36.5 minutes, respectively. These values were decreased to 8.1 minutes and 18.1 minutes, respectively, by doxapram, and to 3.5 minutes and 19.9 minutes, respectively, by doxapram + yohimbine. Doxapram, 4-AP + doxapram, and doxapram + yohimbine caused periodic extensor rigidity before and during arousal. This rigidity was accompanied by opisthotonos in 2 dogs of the doxapram + yohimbine group and may have been mild tonic seizures.(ABSTRACT TRUNCATED AT 250 WORDS)

4-Aminopyridine↗
PubMed1984

Comparison of five preanesthetic medicaments in thiopental-anesthetized cats: antagonism by selected compounds.

Effects of IM injections of saline solution (groups 1, 2, 3, and 4), xylazine (2.2 mg/kg of body weight, groups 5 and 6), acepromazine (0.11 mg/kg, groups 7 and 8), ketamine (11 mg/kg, groups 9 and 10), meperidine (4.4 mg/kg, groups 11 and 12), and diazepam (1 mg/kg, groups 13 and 14) were compared in atropinized cats. Treated cats were anesthetized to loss of palpebral reflex with thiopental, IV. Within 2 minutes, the cats were given IV injections of 0.15 mg of 4-aminopyridine (4-AP) with 0.125 mg of yohimbine/kg (groups 2, 6, 8, and 10), 0.04 mg of naloxone/kg (groups 3 and 12), or 5 mg of the benzodiazepine antagonist Ro 15-1788/kg (groups 4 and 14). Groups 1, 5, 7, 9, 11, and 13 were given saline solution instead of the test antagonists. Required doses of thiopental, arousal time, walk time (measured from injection of antagonists), respiratory rate, and heart rate were recorded. Induction phenomena were also recorded. Emergence was graded as smooth, fairly smooth, fairly smooth in some cats to fairly rough in other cats, rough, or very rough. In group 1 cats, mean arousal time (MAT) was 20.1 minutes, mean walk time (MWT) was 50 minutes, and emergence was rough. In groups given saline solution as the antagonist, the MAT, MWT (both expressed in minutes), and emergence, respectively, were: group 5 = 52.5, 65.5, smooth; group 7 = 15.6, 36.2, fairly smooth; group 9 = 22.5, 58.1, rough; group 11 = 31.3, 52.7, fairly smooth to fairly rough; and group 13 = 91.8, 427, very rough.(ABSTRACT TRUNCATED AT 250 WORDS)

4-Aminopyridine↗
PubMed1984

Caprine aflatoxicosis: serum electrophoresis and pathologic changes.

Pathologic changes and serum electrophoretic patterns were determined in 30 male goats given aflatoxin B1 (AFB1) orally at 4 dosage levels (mg/kg of body weight/day): 0.1 for 34 days; 0.2 for 18 days; 0.4 for 10 days; or 0.0 for 29 days. Goats given AFB1 had increased mean concentrations of gamma-globulins and most had decreased mean concentrations of beta-globulins, although these changes in serum proteins were not significant (P greater than 0.05). At necropsy, ascites, pale livers, petechial hemorrhages, nasal discharge, and icterus were present. Microscopic changes included bile ductule proliferation, hepatocytic karyomegaly, hepatocellular degeneration, pneumonia, rhinitis, and proximal renal tubular nephrosis. Goats given the 2 smaller dosage levels of AFB1 lived longer and had more severe lesions. Goats may be a good model for the study of ruminant aflatoxicosis.

Aflatoxin B1↗
PubMed1984

Caprine aflatoxicosis: experimental disease and clinical pathologic changes.

Groups of 8 male crossbreed domestic goats were given 3 dosage levels of aflatoxin B1 [(AFB1) mg/kg of body weight/day] orally: 0.1 for 34 days; 0.2 for 18 days; or 0.4 for 10 days. Clinical condition, feed consumption, and selected blood values were determined. Clinical signs of toxicosis included decreased feed consumption, slight-to-moderate loss of body weight, mucopurulent nasal discharge, dyspnea, coughing, lethargy, icterus, diarrhea (4 goats), and subnormal body temperature 24 to 48 hours before death. Clinicopathologic changes included increases in total RBC count, PCV, hemoglobin concentration, serum bilirubin concentration, and serum activities of aspartate aminotransferase, isocitric dehydrogenase, and ornithine carbamyl transferase. Goats given the 2 smaller dosage levels of AFB1 had slight increases of serum total protein (TP) concentration compared with control goats, but goats given the larger dosage levels of AFB1 initially had a slight decrease in TP. Aflatoxin had little effect on total WBC count. Serum alanine aminotransferase (ALT) activities in goats given the 2 larger dosage levels of AFB1 were similar to those of control goats, but goats given the smallest dosage level of AFB1 had increased serum ALT activities. Aflatoxin did not produce consistent dose-related changes in serum alkaline phosphatase activities. Seemingly, goats are susceptible to aflatoxin. Onset of clinical signs was dose-related. Onset and magnitude of increases in PCV, hemoglobin concentration, serum bilirubin concentration, and activities of serum aspartate aminotransferase, ornithine carbamyl transferase, and isocitric dehydrogenase were dose-related. Changes in TP and activities of serum ALT and alkaline phosphatase were neither dose-related nor were they potentially useful indicators of toxicosis.

Acute Disease↗
PubMed1984

Antagonism of xylazine sedation in steers by doxapram and 4-aminopyridine.

Five groups of 6 fasted crossbred steers were injected IM with standard dosages of xylazine hydrochloride (0.3 to 0.5 mg/kg). At maximal sedation, the steers were injected IV with the antagonists' doxapram (1.0 mg/kg), doxapram + yohimbine (0.125 mg of yohimbine/kg), doxapram + 4-aminopyridine (4-AP; 0.3 mg of 4-AP/kg), or 4-AP + yohimbine. One group was given 1.0 ml of saline solution IV instead of antagonists. Doxapram, doxapram + yohimbine, doxapram + 4-AP, and 4-AP + yohimbine decreased mean standing time (time from antagonist injection until animal could stand unaided) to 17.0, 4.3, 3.3, and 4.5 minutes, respectively--significantly (P less than 0.05) down from a control value of 49.8 minutes. Mean total recovery time (time from xylazine injection until animal resumed eating) was decreased to 78 minutes by doxapram and 81.6 minutes by doxapram + 4-AP--significantly (P less than 0.05) down from the control value of 142.9 minutes. Respiratory character was improved (depth of respiration was increased) only by doxapram + 4-AP. Relapses to recumbency and marked sedation were not seen in steers given doxapram + 4-AP or the saline solution. One steer given doxapram, 2 given doxapram + yohimbine, and 1 given 4-AP + yohimbine relapsed to recumbency and sedation. Recovery was relatively smooth in steers given doxapram + 4-AP or 4-AP + yohimbine. Animals given doxapram or doxapram + yohimbine had difficult recoveries.(ABSTRACT TRUNCATED AT 250 WORDS)

4-Aminopyridine↗
PubMed1984

Reversal of pentobarbital anesthesia with 4-aminopyridine and yohimbine in cats pretreated with acepromazine and xylazine.

In 2 separate experiments, groups of atropinized cats (6 cats/group) were given acepromazine (0.25 mg/kg of body weight) or xylazine (2.2 mg/kg) IM and anesthetized with pentobarbital. The mean dose of pentobarbital was decreased approximately 36% by acepromazine, and approximately 80% by xylazine, compared with published doses. Anesthetized cats were given IV saline solution (control groups) or were given the antagonists 4-aminopyridine (4-AP; 0.5 mg/kg), yohimbine (0.4 mg/kg), or 4-AP + yohimbine (0.5 mg/kg and 0.4 mg/kg, respectively). In acepromazine-treated cats, 4-AP + yohimbine was the most effective antagonist; arousal and walking occurred in an average of 10.4 minutes and 91.7 minutes, respectively. Yohimbine enhanced the antagonistic effects of 4-AP. In xylazine-treated cats, yohimbine was an effective antagonist; arousal and walking occurred in an average of 2.8 minutes and 12.8 minutes, respectively. Yohimbine did not enhance the antagonistic effects of 4-AP. Mean respiratory rates were decreased by acepromazine, but were increased by xylazine. Thus, respiratory rate depression by pentobarbital was not as marked with xylazine as it was with acepromazine. Changes in mean heart rate were not remarkable with either sedative, and cardiac irregularities were not palpated or auscultated. In healthy cats, the duration of pentobarbital anesthesia can be controlled by 4-AP + yohimbine (acepromazine-pretreated cats) or by yohimbine alone (xylazine-pretreated cats).

4-Aminopyridine↗
PubMed1984

Meperidine-acepromazine-pentobarbital anesthesia in cats: reversal by 4-aminopyridine and yohimbine.

Groups of atropinized cats (6/group) were given IM meperidine (5.5 mg/kg of body weight) plus acepromazine (0.25 mg/kg). Forty minutes later, the cats were anesthetized to disappearance of pedal reflexes with 1% pentobarbital IV. Volume of anesthetic was recorded. Five minutes later, the cats were given IV saline solution (2 ml; control group), the antagonists 4-aminopyridine (4-AP; 0.5 mg/kg), yohimbine (0.4 mg/kg), or a combination of 0.5 mg of 4-AP/kg plus 0.4 mg of yohimbine/kg. Mean arousal time (MAT), walk time (MWT), respiratory rate, and heart rate were measured. Emergence phenomena also were recorded. Meperidine plus acepromazine caused mydriasis and mild sedation without ataxia or marked protrusion of the 3rd eyelid. The cats did not resist restraint for venipuncture. The pooled mean dosage level of pentobarbital required for anesthesia was 12.3 mg/kg. Control group MAT and MWT were 66.2 minutes and 126 minutes, respectively. Marked residual sedation lasted several hours. In cats given 4-AP plus yohimbine, MAT and MWT were decreased to 4.4 minutes and 36.5 minutes, respectively. These values were not significantly shorter than those same values in cats given 4-AP or yohimbine alone (P greater than 0.05), but the combination of 4-AP plus yohimbine produced a qualitatively better reversal of anesthesia than did 4-AP or yohimbine alone. Emergence was smooth in all 4 groups; mild-to-moderate residual sedation lasted 2 to 4 hours in the principals. Relapses, drug side effects, and behavioral aberrations were not observed. Mean respiratory rates and heart rates decreased during anesthesia but these values were not excessively depressed or stimulated at any time. Cardiac irregularities were not detected by palpation or auscultation.(ABSTRACT TRUNCATED AT 250 WORDS)

4-Aminopyridine↗
PubMed1984

Antagonism of xylazine and ketamine anesthesia by 4-aminopyridine and yohimbine in geldings.

Thirty-six fasted, mixed horse breed geldings (6 groups of 6 animals each) were anesthetized with xylazine and ketamine, and when maximally sedated, were given 1 of the following antagonists: saline solution, 4-aminopyridine (4-AP), small-dose yohimbine, large-dose yohimbine, 4-AP plus low-dose yohimbine, or 4-AP plus high-dose yohimbine. Measured data included mean standing time (MST), heart rate, respiratory rate, rectal temperature, and mean total recovery time ( MTRT ). Emergence phenomena were also observed and recorded as smooth, fairly smooth, fairly rough, or rough. Groups given 4-AP alone, small-dose yohimbine alone, or large-dose yohimbine alone produced a significant (P less than 0.05) decrease in MST (9.9 +/- 1.6 minutes, 11.3 +/- 1.7 minutes, and 10.6 +/- 2.3 minutes, respectively) compared with that in the saline control group (24.3 +/- 9.2 minutes). The MTRT were not significantly (P greater than 0.05) different (47.2 +/- 10 minutes, 90.4 +/- 15.1 minutes, and 83.2 +/- 23 minutes, respectively) from control values (66.2 +/- 13.4 minutes). When the antagonists were combined, 4-AP plus small-dose yohimbine and 4-AP plus large-dose yohimbine produced significant (P less than 0.05) decreases (10.3 +/- 2 minutes and 8.3 +/- 2.6 minutes, respectively) in MST compared with that of saline controls. The MTRT was significantly longer in the combined antagonist group (4-AP + small-dose yohimbine--131.8 +/- 28.9 minutes; 4-AP + large-dose yohimbine--131.3 +/- 19.4 minutes) compared with that of control or any antagonist alone.(ABSTRACT TRUNCATED AT 250 WORDS)

4-Aminopyridine↗
PubMed1983

Acepromazine-xylazine combination in dogs: antagonism with 4-aminopyridine and yohimbine.

Groups of fasted atropinized crossbred dogs of both sexes were injected IM with a standard dosage of a xylazine-acepromazine combination (2.2 mg/kg and 0.5 mg/kg, respectively). Righting reflex was uniformly lost and considered to be the point of maximum sedation. After maximal sedation, dogs were injected IV with 4-amino-pyridine (4-AP, 0.5 mg/kg), yohimbine (0.25 mg/kg), or a combination of 4-AP and yohimbine. Controls were given (IV) 1 ml of saline solution. The 4-AP, yohimbine, and 4-AP + yohimbine significantly reduced walk times (time to arousal and ability to walk on a leash) from a control value of 43.1 minutes to 7.6, 4.4, and 1.9 minutes, respectively (P less than 0.05). Relapse to unconsciousness did not occur with any antagonist regimen and recovery was uneventful. In 3 dogs sedated with the xylazine-acepromazine combination supplemented with halothane having surgically placed cannulas and electrodes for measurement of electroencephalo-, electrocardio-, and electromyographic (EEG, ECG, and EMG) responses, arterial blood pressure, and respiratory rates and depth, IV injection of 4-AP + yohimbine caused transient femoral arterial hypotension with tachycardia, increases in respiratory rate, depth, and minute volume, increased EMG and EEG activities preceding and accompanying gross movements, slight speeding of ECG, and behavioral arousal within 3 minutes. Increased heart rate also was observed in intact dogs given yohimbine. Increased rate and depth of respiration also was seen in all intact dogs given antagonists. Curiously, the xylazine-acepromazine combination did not induce arterial hypotension as expected from the product literature. To what extent pretreatment with atropine sulfate may have counteracted this effect is unknown.(ABSTRACT TRUNCATED AT 250 WORDS)

4-Aminopyridine↗
PubMed1983

Comparison of five preanesthetic medicaments in pentobarbital-anesthetized dogs: antagonism by 4-aminopyridine, yohimbine, and naloxone.

Effects of saline solution (groups 1, 2, and 3), xylazine (2.2 mg/kg of body weight, groups 4 and 5), acepromazine (0.1 mg/kg, groups 6 and 7), diazepam (1.0 mg/kg, groups 8 and 9), morphine (1.0 mg/kg, groups 10 and 11), or fentanyl-droperidol (0.055 ml/kg, groups 12 and 13), IM were compared in groups of atropinized dogs. Treated dogs were anesthetized to stage III, plane 2 with pentobarbital, IV. After stabilization of anesthesia, the dogs were given IV 0.5 mg of 4-aminopyridine (4-AP)/kg + 0.25 mg of yohimbine/kg (groups 2, 5, 7, and 9), or 4-AP + yohimbine + 0.04 mg of naloxone/kg (groups 3, 11, and 13). Groups 1, 4, 6, 8, 10, and 12 were given saline solution instead of test antagonists. Required dosage of pentobarbital, arousal and walk times (measured from injection of antagonists), respiratory rate, and heart rate were measured. Emergence phenomena were recorded and graded as smooth, fairly smooth, smooth in some dogs to rough in other dogs, rough, or very rough. In group 1 dogs, mean arousal time (MAT) was 279.5 minutes, mean walk time (MWT) was 583.3 minutes, and emergence was rough. In groups 4, 6, 8, 10, and 12, MAT was decreased by the sedatives to the range of 52 to 115.3 minutes and MWT was decreased to the range of 82.3 to 188.5 minutes. Emergence was smooth (groups 4 and 6), fairly smooth (groups 10 and 12), or smooth to rough (group 8).(ABSTRACT TRUNCATED AT 250 WORDS)

4-Aminopyridine↗
PubMed1982

Antagonism of xylazine sedation by 4-aminopyridine and yohimbine in cattle.

Twenty-four crossbred steers (4 groups of 6 steers each) were injected IM with a standard dosage range of xylazine hydrochloride (0.2 to 0.3 mg/kg of body weight). When the steers were maximally sedated, group I (control group) were given isotonic saline solution (1 ml, IV), group II were given 4-aminopyridine (4-AP, 0.3 mg/kg) IV, group III were given yohimbine hydrochloride (0.125 mg/kg) IV, and group IV were given 4-AP (0.3 mg/kg) plus yohimbine hydrochloride (0.125 mg/kg) IV. The 4-AP decreased mean standing time (MST; time until animal could stand unaided) from 94.3 minutes (control) to 13.4 minutes. Yohimbine decreased MST to 27 minutes. The combination of 4-AP + yohimbine decreased MST to 7.4 minutes. Mean total recovery time (MTRT; time from xylazine injection until normal behavior, including eating and drinking) was not significantly (P = greater than 0.05) decreased from control values by any of the antagonists tested. The combination of 4-AP + yohimbine decreased MST in animals given a 3X overdose of xylazine (0.6 mg/kg) from 124 minutes (control) to 30.3 min. The MTRT was not significantly (P greater than 0.05) decreased from control values. Two animals given a 5X overdose of xylazine (1 mg/kg) and then given 4-AP + yohimbine had a MST of 32.5 minutes and a MTRT of 3.7 hours. The combination of 4-AP + yohimbine produced marked antagonism of xylazine sedation in cattle. The combination of antagonists may prove to be useful for the arousal of animals sedated with xylazine alone or with a combination of sedatives including xylazine.

4-Aminopyridine↗