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Biomedical subjects

J K Walters

Publications and source records attributed to J K Walters.

25 records · Page 2Linked to original sources
PubMed1977

Effects of PCPA on the consumption of alcohol, water and other solutions.

The influence of para-chlorophenylalanine (PCPA) on the preference for alcohol, saccharin, glucose, and sodium chloride solutions and on water intake was studied in rats. Ten daily intragastric doses of 100 mg/kg PCPA were found to reduce alcohol preference both during and after PCPA treatment. Administration of daily 20 mg/kg IP doses of 5-hydroxtryptophan (5-HTP), plus a peripheral decarboxylase inhibitor, failed to reverse the PCPA-induced suppression in the post-PCPA test. Alcohol preference was not reduced below baseline following PCPA if this drug was administered between preference tests rater than coincident with alcohol drinking. Preference for saccharin, glucose, and sodium chloride solutions were all affected by PCPA. Large increases in water intake were produced by 50, 100, or 200 mg/kg PCPA given orally for 10 days. These experiments suggest that alcohol preference, in studies where PCPA treatment and alcohol drinking occur concurrently, may be considerably influenced by learned aversions to alcohol. Also, PCPA may, under some circumstances, produce an increased consumption of water by rats.

5-Hydroxytryptophan↗
PubMed1977

Psilocybin: biphasic dose-response effects on the acoustic startle reflex in the rat.

The startle reflex was measured in 7 groups of 10 rats each after intraperitoneal injection of saline or 0.25, 0.50, 0.75, 1.0, 2.0, 4.0 or 8.0 mg/kg psilocybin. Low doses (0.75-2.0 mg/kg) increased startle amplitude whereas high doses (4.0-8.0 mg/kg) depressed startle. Selected low (0.71 mg/kg) or high (5.70 mg/kg) doses of psilocin also had a biphasic dose-response effect on startle comparable in magnitude to equimolar doses of psilocybin. This biphasic dose-response relationship of the indole hallucinogen, psilocybin, on startle is consistent with the hypothesis that startle is increased when the firing rates of midbrain raphe neurons are selectively inhibited but is depressed when neurons postsynaptic to raphe cells are also inhibited.

Acoustic Stimulation↗
PubMedDate not supplied

Effect of metoclopramide on prolonged intraesophageal pH testing in infants with gastroesophageal reflux.

The effect of metoclopramide (MCP) on prolonged intraesophageal pH testing was evaluated in 42 infants with gastroesophageal reflux (GER). Following a baseline period of intraesophageal pH monitoring, MCP was administered by injection at 0.1 mg/kg/dose (10 patients), 0.2 mg/kg/dose (11 patients), or 0.3 mg/kg/dose (21 patients). The percentage of time of intraesophageal pH less than 4, reflux frequency, and acid clearance time were calculated for each subject before and after MCP for both 5% dextrose and formula feedings. These parameters were further separated into 2-hour or shorter and more than 2-hour postprandial periods. No significant differences with either type of feeding were noted at either 0.1 or 0.2 mg/kg/dose. Significant decreases in the percentage of time the intraesophageal pH was less than 4 (30.0 +/- 2.9 versus 15.6 +/- 3.1, p = 0.001), the reflux frequency (episodes/hour; 6.5 +/- 0.9 versus 4.0 +/- 0.6, p = 0.004), and the acid clearance time (minutes/episode; 3.8 +/- 0.7 versus 2.2 +/- 0.3, p = 0.047) were noted in the 2-hour or shorter period following 5% dextrose feedings but not following the formula feedings in the subjects receiving 0.3 mg/kg/dose. Three of the 42 study patients developed increased irritability, and one developed dystonia following MCP. These data suggest that if a clinical trial of MCP in infants with GER is performed, a larger dose of the medication than previously appreciated might be required.

Esophagus↗