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Biomedical subjects

I J Kopin

Publications and source records attributed to I J Kopin.

At least 19 recordsLinked to original sources
PubMed1979

Differential effects of d- and l-propranolol on dopamine turnover stimulated by oxotremorine in striatal and mesolimbic areas of rat brain.

The effects of l-propranolol, d-propranolol and clonidine on homovanillic acid (HVA) concentrations in the corpus striatum and nucleus accumbens of rats were studied under normal conditions and after treatment with oxotremorine or haloperidol. Thile propranolol and clonidine given alone had no significant effect on HVA levels in either area, l-propranolol (1--10 mg/kg) and clonidine (0.1 mg/kg), both significantly inhibited the elevation of striatal HVA, found 60 min after oxotremorine administration. Both l- and d-propranolol (2.5 mg/kg), reduced the effect of oxotremorine in the nucleus accumbens. Neither l-propranolol no clonidine affected the rise in HVA in either brain area seen after haloperidol. Our results suggest that propranolol may reduce cholinergic activation of dopaminergic pathways by two different mechanisms. One is stereospecific for the l-isomer and operates in the striatum and another, which is shared by both isomers, occurs in the nucleus accumbens.

Animals↗
PubMed1979

Plasma levels of d-amphetamine in hyperactive children. Serial behavior and motor responses.

Amphetamine has been clearly documented to be an efficacious treatment for hyperactive children. The pharmacokinetics of amphetamine have been studied in adults, but not in children. Sixteen male children who scored greater than 2SD from norms on Factors I and IV of Conner's Teacher Rating Scale and who were not excluded for reasons to do with medical or psychiatric conditions, intelligence, or age, had a plasma d-amphetamine apparent elimination half-life of 6.8 +/- 0.5h. Peak plasma level occurred between 3 and 4h (62.7 +/- 3.8 and 65.9 +/- 3.6 ng/ml, respectively). Six of these children had a repeat study and there were no significant differences within subject in apparent elimination half-lives and attained peak blood levels. The variation in plasma levels was greater during absorption than during elimination. Both behavioral and motor activity responses as analyzed by differences between amphetamine and placebo days (by paired t-tests) indicate significant responses between hours 1--4; however, these responses do not correlate with plasma amphetamine levels; they occur during the absorption phase. The decreased response to later similar plasma levels of d-amphetamine may be related to depletion of catecholamine stores, to replacement by a 'false neurotransmitter' metabolite of amphetamine, or to alteration in receptor sensitivity.

Child↗
PubMed1979

Electrolytes and norepinephrine levels in blood of patients with cystic fibrosis.

Young adults with cystic fibrosis in good to excellent condition have reduced plasma sodium and chloride and elevated plasma potassium compared to a group of healthy young adult control subjects. Blood pressure was also lower in the patients with cystic fibrosis. However, plasma norepinephrine and dopamine-beta-hydroxylase and their response to standing and isometric hand grip were normal in the cystic fibrosis patients.

Adolescent↗
PubMed1979

Adrenaline, noradrenaline and dopamine levels in specific brain stem areas of acutely immobilized rats.

Catecholamines (adrenaline, noradrenaline and dopamine) have been measured in specific areas of the rat brain stem after acute immobilization stress. Adrenaline levels were significantly decreased after 240 min of immobilization in all areas studied: A1 area, nucleus commissuralis (NCO), A2 area, anterior part of the nucleus tractus solitarii (NTS), and the locus coeruleus. Noradrenaline concentrations in stressed rats were significantly reduced only in the NTS area. In contrast, during stress there were no significant changes in dopamine concentrations with respect to control values in any of the areas studied. These results implicate the participation of central adrenaline neurons, localized in specific brain stem areas, and noradrenaline neurons innervating the rostral part of the nucleus tractus solitarii, in the mechanism of central response to acute stress.

Animals↗
PubMed1979

Hydrochlorothiazide-induced sympathetic hyperactivity in hypertensive patients.

Hydrochlorothiazide-induced diuresis and natriuresis is considered to be responsible for the antihypertensive effect of this drug. After short-term treatment there is decreased cardiac output and increased peripheral resistance which we have found to be attended by increased plasma norepinephrine (NE) levels. After longer treatment cardiac output returns to normal and peripheral resistance declines. At this time, plasma NE levels remain elevated, indicating that peripheral resistance reduction is not a consequence of a reduction of the elevated level of sympathetic activity. These results provide a rationale for the combined use of diuretics and drugs which diminish noradrenergic activity in the treatment of hypertension.

Adult↗
PubMed1979

Effect of imipramine on norepinephrine and blood pressure in enuretic boys.

The effect of imipramine, desmethylimipramine, and methscopolamine on blood pressure (BP) and plasma norepinephrine (NE) was measured in enuretic boys in a double-blind, placebo-controlled study. Measurements were obtained on the thirteenth day of medication (75 mg at bedtime). The tricyclic drugs induced a rise in diastolic BP as well as an increase in plasma NE but there was no significant relationshhip between the increments in plasma NE and BP. The plasma concentration of drug correlated with the drug-induced BP rise. This is the fifth study to demonstrate a hypertensive effect of tricyclic drugs in children in contrast to the systolic hypotension usually seen in adult patients. It is not clear from our data whether children have different cardiovascular compensatory reflexes or whether they experience a greater stimulant effect from the drug.

Blood Pressure↗
PubMed1979

Patterns of behavioral development in spontaneously hypertensive rats and Wistar-Kyoto normotensive controls.

We have examined the behavior of spontaneously hypertensive (SHR) rats and stroke-prone hypertensive (SP-SHR) male rats during the development and maintenance of elevated blood pressure and compared this pattern with age- and gender-matched normotensive (WKY) rats of the same Wistar-Kyoto strain as controls. Rats of each strain (n = 10/age group) were isolated in individual cages and observed for 60 min at 3,4,6,8,10, or 20 weeks of age using a scan sampling technique. At all ages SHR rats were significantly more active than WKY rats whereas SP-SHR rats were intermediate in level of activity. In a 2nd series, activity of male rats of each strain was monitored continuously for 24 hr in the home cage. No strain differences in amount or pattern of total daily activity were evident at either 4-6 or 16-18 weeks of age. These results indicate that SHR rats are more reactive to environmental change, but the intermediate level of activity of SP-SPHR rats suggests that this response is not related to the degree of blood pressure elevation,

Age Factors↗
PubMed1979

Chronic Parkinsonism secondary to intravenous injection of meperidine analogues.

Abuse of 4-propyloxy-4-phenyl-N-methylpiperidine, a meperidine congener, produced parkinsonism in a 23-year-old man. Unlike other drug-induced motor disturbances, the syndrome persisted for 18 months and responded to drugs that stimulate dopamine receptors. Biogenic amines and metabolites in the cerebrospinal fluid and microscopic evaluation of the brain at necropsy were consistent with damage to aminergic neurons in the substantia nigra.

Adult↗