Search PubMed⌕ Search

Biomedical subjects

J L Falk

Publications and source records attributed to J L Falk.

At least 145 records · Page 8Linked to original sources
PubMed1967

Control of schedule-induced polydipsia: type, size, and spacing of meals.

Rats were given daily 1-min variable-interval sessions for several types of food delivered in various amounts per reinforcement and the concurrent, schedule-induced polydipsia was measured. Dry, solid food was neither a necessary nor sufficient condition for the development of polydipsia. Small portions of liquid Standard Monkey Diet produced polydipsia, but 45-mg dextrose or sucrose pellets did not. Within the range studied, smaller portions of both solid and liquid foods produced more drinking than larger portions per reinforcement. Two-min variable-interval sessions produced a greater polydipsic response than 1-min variable-interval, even though the number of 45-mg Noyes pellets allowed per session was held constant. Polydipsia was greatly attenuated on these schedules when the number of pellets remained constant, but were delivered two at a time. Within the ranges studied, the concurrent polydipsic response was increased by decreasing the rate of food acquisition, either by using smaller portions of food per reinforcement or by increasing the interreinforcement time.

Animals↗
PubMed1966

Analysis of water and NaCl solution acceptance by schedule-induced polydipsia.

Animals were trained on a VI 1-min schedule for food pellets, and concurrent water intake was measured. The polydipsia induced was analyzed in terms of the frequency distribution of post-pellet licking burst sizes and the trend of polydipsia throughout the session. An ascending series of NaCl solutions was presented consecutively over daily sessions and a typical NaCl acceptance-rejection intake function was generated. Beginning in the 0.9-1.2% NaCl range, the animals drank less often during the session but took larger drinks when they did drink. Neither the frequency of drinks nor the mean licking burst size were simply related to the volumes of NaCl solution consumed. The NaCl acceptance-rejection function cannot be explained in terms of water repletion factors alone.

Animals↗
PubMed1966

The motivational properties of schedule-induced polydipsia.

Schedule-induced polydipsia occurred during initial magazine training to Noyes pellets (45 mg), disappeared when lever-pressing was acquired on a continuous reinforcement schedule (CRF), and reappeared when the food contingency was changed to a 1-min variable interval schedule (VI 1 min). Polydipsia also developed under a VI 1 min food schedule when water was concurrently available on various fixed ratios (FR), rather than being freely available. The level of the polydipsia and its motivating properties allow it to be classified as a form of adjunctive behavior.

Animals↗
PubMed1966

Schedule-induced polydipsia as a function of fixed interval length.

Rats were trained to bar-press for Noyes pellets on an FI schedule which was increased serially through several values from 2 sec to as high as 300 sec. Concurrently, water was freely available. As FI length was increased, the degree of polydipsia increased linearly to a maximum value.

Animals↗
PubMedDate not supplied

Pattern of daily blood ethanol elevation and the development of physical dependence.

Schedule-induced ethanol polydipsia regimens were used which produced either one or two daily peaks in blood ethanol levels. After 3 months on these regimens, rats were withdrawn from ethanol and tested for the presence of abstinence signs. No evidence of physical dependence was found, a result which contrasted with the previous finding of a severe withdrawal syndrome when blood ethanol was maintained at a more continuously elevated level prior to withdrawal. It was concluded that, as in the case of barbiturates, the development of physical dependence on ethanol requires more than an episodic peaking of the blood ethanol level once or twice per day.

Alcohol Drinking↗
PubMedDate not supplied

Dilutional hyponatremia due to diazoxide-produced polydipsia.

Subcutaneous injection of diazoxide every 3 hr for a total of 5 doses in 15 hr produced a state of elevated drinking and antidiuresis in rats resulting in a massive, positive, self-imposed water load. Dilutional hyponatremia was present, but not serum hyposmolality, owing to the increased serum glucose and BUN. The mechanism by which diazoxide produces a polydipsia even in the presence of an accumulating water load may illuminate the genesis of other pathophysiological dilutional states.

Animals↗
PubMedDate not supplied

Schedule-induced ethanol dependence and phenobarbital preference.

Rats exposed to a daily 3-hr session of intermittent food delivery ingested physical-dependence-produced levels of 5% ethanol solution. Although this schedule induced a chronic, voluntary, daily overindulgence, this had no effect on 21-hr home-cage phenobarbital preference. The substitution of water for 5% ethanol during the daily 3-hr binge session did not change home-cage phenobarbital preference, which remained stable and similar to that of a control group of non-binging animals. This experiment and others indicate that physical dependence on ethanol does not play a major role in the maintenance of ethanol abuse or cross-abuse of the barbiturates.

Alcohol Drinking↗
PubMedDate not supplied

Ethanol polydipsic choice: effects of alternative fluid polydipsic history.

Two groups of rats drinking either 5% ethanol or 0.9% NaCl solution under a fixed-time 1-min schedule of food pellet delivery became polydipsic during daily 3-hr sessions. When both fluids were made available to animals during sessions, strong side preferences typically developed so that neither fluid was preferred in spite of the fact that one group had a mild-to-moderate physical dependence on ethanol. The group that drank 0.9% NaCl solution initially failed to acquire a strong 5% ethanol polydipsia when this became the sole available fluid, and special procedures were required to induce an ethanol polydipsia comparable to that of the other group. Hence, a history of 0.9% NaCl solution polydipsia interfered with the institution of chronic, ethanol overdrinking in this group. Equal ethanol intakes were maintained in the groups when a compound solution consisting of 5% ethanol plus 0.9% NaCl solution was available along with a 5% ethanol choice. Whenever a 0.9% NaCl solution was presented in competition with either 5% ethanol or the compound 5% ethanol plus 0.9% NaCl solution, ethanol intake was reduced. Implications for the prevention and amelioration of human ethanol overdrinking are discussed.

Alcohol Drinking↗