Curve In Rats Research Articles

Sodium preferences and responses to sodium deficiency in rhesus monkeys

Rhesus monkeys were offered sodium chloride (NaCl) in various concentrations before and during the imposition of a dietary sodium deficiency. No evidence of a preference-aversion curve for NaCl appeared, providing support for the “dilute-water” hypothesis explaining sodium preference-aversion curves in rats. (Rhesus monkeys have separate sensory channels for water and salt, while rats have a combined water-salt sensory channel.) Although urinary and serum sodium levels were reduced during the period of sodium deficiency, there was no increase in the voluntary ingestion of NaCl during deficiency. However, three separate behavioral and physiological adaptations to sodium deficiency appeared among the monkeys.

Neurotoxicity of topically applied hexachlorophene in the young rat.

Young rats 6 to 22 days of age are extremely susceptible to the neurotoxic effects of hexachlorophene given as a daily bath of undiluted antiseptic detergent containing 3% hexachlorophene (pHiso-Hex). At this age, most rats are clinically and histologically damaged by as few as two daily baths. Younger rats are relatively resistant, probably because they have less myelin to be affected; older rats cannot be poisoned by this route, probably because the more mature liver excretes the drug more effectively. Age-dose-response curves in rats are similar to those in humans. This experimental model is potentially useful in defining other characteristics of this drug.

Shifting of the d-amphetamine dose-response curve in rats with frontal cortical ablations.

Rats trained to bar-press on a FI 15 sec schedule for water reinforcement were administered various doses of d-amphetamine (0.25–4.0 mg/kg) both before and 6–8 weeks after bilateral ablation of frontal cortex. Preoperatively, low doses (e.g. 0.25–0.5 mg/kg) of (d-amphetamine increased responding and high doses (e.g. 2.0–4.0 mg/kg) of d-amphetamine depressed responding. Postoperatively, frontal rats showed larger facilitatory effects in response to low doses of d-amphet-amine but lesser depressant effects in response to high doses of d-amphetamine; the whole dose-response curve was generally shifted higher by the frontal lesions. These results indicate that frontal lesions differentially influence mechanisms mediating two different actions of d-amphetamine.

Plasma amino acid curve in rats force-fed a single meal lacking an essential amino acid

The amino acid levels in plasma and liver were determined in rats at various time intervals after giving the animals a single meal of a complete amino acid diet (CAA) or a diet devoid of either leucine, isoleucine, or threonine. Male rats were fed by stomach tube and they were killed at 0, 2, 4, 6, or 8 hours postprandial. Amino acid analyses were performed on deproteinized supernatants of plasma and liver. The changes in the plasma amino acid levels occurred within 2 hr after feeding a single meal of either the diet lacking leucine or CAA. The values of most of the amino acids attained their highest levels at 4 hr postprandial and many amino acids were declining in concentration at 6 and 8 hr. Isoleucine and valine showed very high levels in plasma at 2, 4, 6 and 8 hr after feeding the diet devoid of leucine. The amino acid levels in liver reflected the amino acid concentrations in plasma at each time interval. Rats fed the diets devoid of either isoleucine or threonine demonstrated less alterations in plasma amino acid concentrations with only a few amino acids changed. After giving a single meal the amino acid levels in plasma are transient since many of the amino acids show similar values at the 0- and 8-hr intervals. The alterations in amino acid levels in plasma that occur after feeding are dependent upon both the identity of the essential amino acid omitted from the diet and the postprandial time.

The Relation of Blood Platelet Survival and Distribution to 14C-Serotonin Distribution and Excretion

Abstract1. The distribution of 14C-5-HT following infusion is different from that of endogenous serotonin. One hour after infusion it is, in major part, a function of the distribution of blood platelets.2. The spleen in rats is the site of a pool of platelets. Based on both 14C and platelet recovery data in normal and splenectomized animals, this pool approximates 40 per cent of the total circulating platelets.3. Postsplenectomy thrombocytosis may relate to removal of a platelet reservoir with shift of the platelets normally contained therein to the peripheral circulation.4. The shape of platelet survival curves in rats is neither strictly linear nor curvilinear but normally is determined primarily by age-related processes in the platelet. Platelet survival curves tend to become curvilinear in thrombocytopenic animals, indicating that there is probably an additional small, fixed random loss of platelets from the circulation.5. The disappearance of 14C-5-HT from blood platelets approximates but is not completely representative of the disappearance of the platelets themselves. It is probable that elution from platelets and possibly reutilization of platelet label occurs.

A Survey of Some of the Available Methods of Analysis of the Growth Curves of Rats in Toxicological Tests

A Survey of Some of the Available Methods of Analysis of the Growth Curves of Rats in Toxicological Tests

Depression of Tracer Ion Uptake Curve in Rat Erythrocytes Following Total Body X-Irradiation

Summary1. A method of demonstrating the depression of the erythroid portion of the bone marrow by x-irradiation with the use of Fe59 is presented.2. Graphs of the red cell FeS9 uptake curve in rats at various dosage levels of total body x-irradiation and at varying times after irradiation are given.

Dosage-Mortality in Rats Given Total Body Roentgen Irradiation.

SummaryThe LD50 for total body X-radiation in Wistar rats is 640 ± 5 r with a 30-day endpoint. The time elapsing before 50%percnt; mortality occurs at different doses is a more reliable measure of mortality than the dosage-mortality curve or the dosage-survival time curves for different X-ray doses. The dosage-mortality curve of rats has such a steep slope in the LD50 range that variations in mortality of from O to nearly 100%percnt; may occur in this range because of variations in animals and in the X-ray machine output. Therefore in studies directed toward (therapy or protection of animals given total body ionizing radiation, if the mortality curves are extremely steep as in the rat, dosages in the LD50 range should not be used. Other measures which might be employed are discussed.