ABSTRACT
The effects of repeated amphetamine (AMPH) pretreatment on norepinephrine (NE) neurotransmission in the hypothalamus and hippocampus were assessed using in vivo microdialysis. Rats were pretreated with either saline or an escalating-dose AMPH regimen (1-->10 mg/kg) over 10 consecutive days, and then were withdrawn from AMPH for either 1 day or 30 days, at which time the animals underwent two consecutive days of testing. As expected, repeated treatment with AMPH resulted in time-dependent changes in both spontaneous locomotor activity and in the psychomotor response to a subsequent challenge injection of AMPH. In addition, repeated exposure to AMPH resulted in time-dependent and regionally-specific changes in the basal concentrations of NE in dialysate, and in the NE response to an AMPH challenge. For example, AMPH pretreatment produced a persistent (at least one month) increase in the basal concentration of NE in the hippocampus, but not the hypothalamus, although the response to an AMPH challenge was altered in both structures. It is suggested that AMPH treatment produces adaptations in NE systems that far outlast the acute effects of the drug, and that these may contribute to both transient and more persistent behavioral sequelae associated with the discontinuation of chronic AMPH use.
Subject(s)
Amphetamine/pharmacology , Central Nervous System Stimulants/pharmacology , Hippocampus/drug effects , Hypothalamus/drug effects , Norepinephrine/metabolism , Animals , Hippocampus/metabolism , Hypothalamus/metabolism , Male , Microdialysis , Motor Activity/drug effects , RatsABSTRACT
A 5-month-old girl presented postoperatively with an atrioventricular (A-V) junctional tachycardia at a rate of 245/min following surgical repair of tetralogy of Fallot. The systolic blood pressure dropped to 60 mmHg with this rapid heart rate, and the infant became shocked. Drugs and overdrive pacing were ineffective in suppressing the A-V junctional tachycardia and in improving cardiac output. Ventricular paired pacing was used successfully to halve the mechanically effective ventricular rate and to restore cardiac output. When ventricular paired pacing was stopped after 12 h, the spontaneous rhythm was an atrial rhythm with 1-1 A-V conduction. The patient was discharged in sinus rhythm on the 5th postoperative day.
Subject(s)
Cardiac Pacing, Artificial , Cardiac Surgical Procedures/adverse effects , Tachycardia, Ectopic Junctional/therapy , Tachycardia, Supraventricular/therapy , Cardiac Output, Low/etiology , Cardiac Output, Low/therapy , Electrocardiography , Female , Humans , Infant , Infant, Newborn , Tachycardia, Ectopic Junctional/complications , Tachycardia, Ectopic Junctional/etiology , Tetralogy of Fallot/surgeryABSTRACT
252 symptomatic patients aged 65-79 underwent surgery between 1970 and 1982 for heart valve lesions. Hospital mortality was 11.8%. Analysis of the short and long term results justifies cardiac surgery in elderly patients with valve disease.
