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Biomedical subjects

T Sumi

Publications and source records attributed to T Sumi.

At least 127 records · Page 7Linked to original sources
PubMed1977

Adrenergic regulation of the plasma levels of purine metabolites in the rat.

The effects of i.v. infusions of catecholamines on the plasma levels of uric acid and allantoin were investigated in the conscious rat. Isoproterenol and epinephrine, in this decreasing order of potency, remarkably elevated both uric and allantoin levels. Norepinephrine did not affect these purine metabolite levels. These effects of isoproterenol and epinephrine were completely abolished by propranolol. Phentolamine, on the contrary, slightly potentiated the effects of epinephrine. In contrast to i.v. fusion, s.c. injection of epinephrine had no effect, but, after prior treatment of animals with phentolamine, elicited striking increases in the plasma purine metabolite levels. Catecholamines thus caused hyperuricemia with a rise in plasma allantoin, both effects being mediated via beta-adrenoceptors and alpha-adrenergic mechanism sometimes functions in such a manner as to mask or inhibit this beta-mediated response.

Allantoin↗
PubMed1977

Modification of cortically evoked rhythmic jaw movements by reflex deglutition in rabbits.

In rabbits, lightly anesthetized with ether, tetanic stimulation of the superior laryngeal nerve (SLN) displaced the jaw toward opening and reduced the amplitude of cortically evoked rhythmic jaw movements. With increased intensity of stimulus, the effects became remarkable and the opened jaw movement ultimately ceased. Reflex swallowing in reaction to weak electrical stimuli of SLN or to a small amount of water squirted into the oropharynx yielded a brief and instantaneous cessation of rhythmic jaw movements with the jaw open. Strong electrical stimuli to the nerve or a squirt of relatively large amount of water into the oropharynx prolonged the duration of both swallowing and the cessation of rhythmic jaw movements for about 1.0 sec. Reflex swallowing yielded a burst of activity for about 300 msec in the mylohyoideus and silence for a longer period in the masseter. Spontaneous activity of the masseter was moderately decreased during the nerve stimulation and, when swallowing occurred, this decrease became prominent for a short period.

Animals↗
PubMed1976

The enzymatic spectrofluorimetric determination of uric acid in microsamples of plasma by using p-hydroxyphenylacetic acid as a fluorophor.

A sensitive spectrofluorimetric micromethod for the determination of uric acid is presented together with its application to human and rat plasma. The method is based on the reactions or uricase and peroxidase coupled with p-hydroxyphenylacetic acid as a fluorophor. There is a very wide range of proportionality between the concentration of uric acid and the increase of fluorescence intensity. 10 ng of uric acid is still determinable. At most 25 mul of human or 50 mul of rat plasma is sufficient to obtain the accurate valve of endogenous plasma uric acid concentration. The uric acid levels of normal human and rat plasma measured by present method were within the ranges of concentrations previously reported. A comparative study of this method with a standard assay method is also presented.

Animals↗
PubMed1975

Potentiation of the adrenergic beta-receptor-mediated insulin secretion in pertussis-sensitized rats.

The increase in blood insulin level induced by adrenergic beta-stimulants, glucose and tolbutamide was strongly exaggerated in pertussis-sensitized rats. Moreover, the decrease in blood insulin caused by the alpha-receptor-mediated action of epinephrine in glucose- or tolbutamide-treated rats was effectively reversed by pertussis sensitization. The rise of blood insulin concentration due to adrenergic alpha-blockade was also enhanced by pertussis sensitization. It is concluded that the secretion of insulin resulting from the stimulation of adrenergic bate-receptor is enhanced by pertussis sensitization, probably due to activation of a process occurring in the chain of events leading to the discharge of insulin from the pancreatic beta-cell.

Animals↗