Biomedical subjects

M J Bakalian

Publications and source records attributed to M J Bakalian.

3 recordsLinked to original sources

PubMed1992

Regulation of cortical blood flow by the dorsal raphe nucleus: topographic organization of cerebrovascular regulatory regions.

We examined in rat: (1) the time-course and magnitude of change in cortical blood flow (CoBF) following electrical stimulation of the dorsal raphe nucleus (DRN) and (2) whether DRN lesions affect resting CoBF or the cerebrovascular response to CO2. Animals were anesthetized (chloralose), paralyzed, and artificially ventilated. The effect of stimulus frequency (1-200 Hz) and intensity (10-100 microA) on arterial pressure, heart rate, and CoBF was examined; lesions were made electrolytically. CoBF was measured using a laser-Doppler flowmeter with the probe placed extradurally over the parietal sensorimotor cortex. The DRN was computer reconstructed in three dimensions from Nissl stained coronal sections for localization of electrode placements. Brief stimuli (8 s; n = 6) elicited frequency and intensity-dependent increases in arterial pressure, heart rate, and CoBF. Sustained intermittent trains of stimuli of rostral DRN (200 Hz; 1 s on/1 s off; 70 microA) elicited a decrease (85 +/- 12% of baseline; n = 9) in CoBF (p less than 0.05) while stimulation in caudal DRN resulted in increased CBF (126 +/- 13% of baseline; n = 9). Phenylephrine infusion (0.1-1 microgram; i.v.; n = 8) increased arterial pressure and CoBF less than that elicited by brief DRN stimulation (p less than 0.05). DRN lesions did not affect resting CoBF (140 +/- 25 perfusion units (PU) before; 127 +/- 16 PU after DRN lesion; p greater than 0.05, n = 5) or mean arterial pressure (127 +/- 13 before; 120 +/- 11 after); nor did it affect the cerebrovascular response to change in arterial PCO2. Sustained intermittent stimulation of the DRN can evoke either increases or decreases in CoBF depending on the anatomical sublocalization. The DRN does not tonically maintain resting CoBF, nor participate in the cerebrovascular response to change in PCO2.

Animals↗

PubMed1990

Effects of L-tryptophan and other amino acids on electroencephalographic sleep in the rat.

Electroencephalographic sleep was quantitated in adult male Sprague-Dawley rats following single injections of the methylesters of tryptophan, valine or alanine. The amino acids were administered at the onset of the daily light period (09.00 h); electrographic data were collected for the succeeding 6-h period. Saline served as the injection control, and fluoxetine, a serotonin-reuptake blocker, as a positive control. The injection of tryptophan methylester (125 mg/kg) caused a delay in rapid eye movement (REM) sleep onset, and significantly reduced the amount of REM sleep during the first 2 h postinjection. Tryptophan produced no effect on sleep onset, nor did it influence total sleep time. Fluoxetine (2.5 mg/kg) produced similar effects, as previously observed. The methylesters of valine and alanine were without effect on REM sleep, when injected at a molar dose equivalent to that for tryptophan. No consistent effects of any of the test substances were noted on non-REM (NREM) sleep or waking time, or on any of the other sleep indices quantitated. Together, the data indicate that tryptophan selectively reduces REM sleep; the effect is not due to a non-specific action of amino acids or their methylesters. The effect on REM sleep may be the consequence of a tryptophan-induced stimulation of 5-HT synthesis and release, since it is like that produced by fluoxetine, a drug that enhances transmission across serotonin synapses.

Alanine↗

PubMed1988

A microcomputer-based sleep system: data acquisition and system calibration programs.

A data acquisition program is described for the Apple II series of microcomputers that allows for continuous, direct monitoring of electrographic elements from cortical, hippocampal and muscle leads from rats. The program detects cortical delta waves and sigma activity, hippocampal theta activity and electromyographic activity. The detected elements are counted and stored in memory at 15 second intervals (bins). Every three hours, the data are transferred to disks for permanent storage and off-line analysis.

Animals↗