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Biomedical subjects

W M Davis

Publications and source records attributed to W M Davis.

At least 91 records · Page 5Linked to original sources
PubMed1978

Acute cocaine intoxication in the conscious dog: pathophysiologic profile of acute lethality.

Cocaine HCl was infused intravenously to conscious mongrel dogs until death (0.5 mg/kg/min; 0.82 ml/min). All animals convulsed (mean convulsive dose: 12 +/- 1 mg/kg) and died approximately 42 min after the beginning of cocaine infusion (mean lethal dose: 21 +/- 2 mg/kg). All animals exhibited significant increases in arterial systolic and diastolic pressures, left ventricular pressure, cardiac output, heart rate, respiratory rate, minute volume, tidal volume, oxygen uptake, plasma glucose, blood lactate and body temperature. Statistically significant reductions from pre-drug control levels were observed in total peripheral resistance, arterial pH, and arterial pO2.

Alanine Transaminase↗
PubMed1977

Alcohol-associated conditioned reinforcement.

Research was conducted to examine the ability of alcohol to impart conditioned reinforcement. Rats were allowed to self-administer solutions of either saline or alcohol (25, 50, and 100 mg/kg/infusion) by the intragastric route. Superimposed on the infusion interval was a buzzer (conditioned reinforcing stimulus). Tests during extinction revealed that conditioned reinforcement had been acquired. Results also indicated that as the paired unit dose was increased, potency of the conditioned reinforcer increased. In a second study, the lever-pressing response, which produced saline infusion and the buzzer, became available only subsequent to 5 sessions of pairing the buzzer with infusions of saline or alcohol. The results indicated that lever pressing increased with increasing unit dosage of alcohol infusions in prior pairings.

Animals↗
PubMed1977

Morphologic aspects of experimental esophageal lye strictures. II. Effect of steroid hormones, bougienage, and induced lathyrism on acute lye burns.

Among 77 dogs surviving standardized transmural esophageal lye injury for at least 2 weeks and as long as 12 weeks, 24 were untreated, 26 received corticosteroids and bougienage (S&B), and 27 received only the lathyrogen beta-aminoproprionitrile (BAPN). Stricture frequency was reduced markedly and significantly in the S&B and BAPN groups when compared to the controls (p less than 0,01). Strictures resulted from inward circumferential remodeling of all mural layers, not proliferating bulky scar tissue, and persistent ulceration was apparently not an influential factor in any group. The S&B dogs invariably showed reduction of the internal or mucosal length of the injured segment as compared to the outer length; these relations were quite variable in the other two groups so that mean internal shortening was significantly greater (p less than 0.01) in the S&B group. Marked mural thinning in the injured zone was present in all three groups but was most frequent in the BAPN-treated animals. The major conclusion is that BAPN-induced changes in the physical properties of reparative tissue can increase the ultimate caliber of an injured hollow viscus without resort to mechanical bougienage. In addition, the data suggest that wound contraction may play a role in stricture formation in this model.

Adrenal Cortex Hormones↗
PubMed1976

Effect of unit dose and route of administration on self-administration of morphine.

Rats were implanted with intravenous or intragastric cannulas and allowed to self-administer morphine sulfate in doses of 0 (saline), 0.03, 0.1, 0.3, 1.0, 3.0, and 10.0 mg/kg/infusion. For the intravenous route the number of infusions decreased with increasing unit dose, while the amount self-administered was directly related to unit dose. However, for the intragastric route the number of infusions first increased and then decreased as unit dose was elevated, while the amount self-administered again increased with unit dose. Comparisons between routes showed that for intragastric subjects the number of infusions and amount self-administered both were lower at the two lowest doses but higher for all other doses. These results support the expectation that intravenous injection should produce more potent reinforcing effects than intragastric administration.

Animals↗
PubMed1976

A dose-response comparison between methadone and morphine self-administration.

Rats were allowed to self-administer a solution of 0.9% saline, or 0.01, 0.03, 0.1 or 0.3 mg/kg/infusion of methadone hydrochloride or 0.03, 0.1 or 0.3 mg/kg/infusion of morphine sulfate. The results showed that number of infusions taken was an inverse function of unit dose, while amount of drug self-administered (mg/kg) was a direct function of unit dose. The data also indicated that more morphine than methadone was self-administered.

Animals↗
PubMed1975

Morphine enhancement of shuttle avoidance prevented by alpha-methyltyrosine.

Rats were given 6 days of training (180 trials) to make a two-way (shuttle) avoidance response. "Poor performers" making less than 50% avoidances in the 6th block of 30 tials were given drug treatments on the next 2 days. Both morphine sulfate (15 mg/kg) and d-amphetamine sulfate (1 mg/kg) increased the avoidance level by 70-100%. Prior treatment with alpha-methyltyrosine (50 mg/kg) prevented the effects of both drugs. Nalorphine hydrochloride (5 mg/kg) also blocked the effect of morphine. The action of alpha-methyltyrosine to block enhancement of avoidance is taken to indicate that this effect of morphine is attributable to a catecholamine-dependent excitatory component of its activity profile.

Animals↗