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T Chiba

Publications and source records attributed to T Chiba.

At least 685 records · Page 38Linked to original sources
PubMed1978

Synaptic structures and quantification of catecholaminergic axons in the nucleus tractus solitarius of the rat: possible modulatory roles of catecholamines in baroreceptor reflexes.

The synaptic organization in the nucleus tractus solitarius (NTS) of the rat at the level of the obex was examined by fluorescence and electron microscopy in 5 groups of animals: (1) normal control, (2) intraventricular injection of 5-OHDA, (3) intraventricular injection of 6-OHDA, (4) intracranial denervation of the IXth and Xth cranial nerves, and (5) intraventricular injection of 5-OHDA 48 h after intracranial denervation of the IXth and Xth cranial nerves. A dense network of catecholaminergic nerves was observed in the NTS and several catecholaminergic neurons were seen to be scattered in the lateral portion of the NTS. Nerve cells in the NTS were small in size (15-20 micrometer in diameter). In addition to ordinary axodendritic and axo-somatic synapses, serial synapses were occasionally encountered. The first presynaptic site in some of the serial synapses was identified as catecholaminergic by 6-OHDA treatment. After treatment with 5-OHDA, 2.4% of axon varicosities were identified as catecholaminergic by small dense-cored vesicles. After administration of 6-OHDA, 5.19% of dense degenerated axon varicosities were counted. After intracranial deafferentation of the IXth and Xth cranial nerves, 5.3% of dense degenerated axon varicosities were found. The total number of axon varicosities in 6800 sq.mum area was decreased by 9% after the injection of 6-OHDA and 11% after deafferentation of the IXth and Xth cranial nerves. At least 3 types of axons could be identified: (1) catecholaminergic axons with small dense-cored vesicles after 5-OHDA administration, (2) afferent axons from the IXth and Xth cranial nerves with small clear vesicles, and (3) axons with small clear vesicles probably originated from the supramedullary nucleus. The results of the present study suggest that catecholamines modulate reflex blood pressure regulation within the NTS of the rat.

Animals↗
PubMed1978

Interneurons of sympathetic ganglia: divergent cyclic AMP responses and morphology in cat and cow.

The biochemical properties of the small, intensely fluorescent (SIF) cells of bovine and feline superior cervical ganglia were determined by studying the cyclic AMP responses to incubation in vitro with adrenergic agonists: the morphological properties were studied by fluorescence histochemistry and electron microscopy. Incubation with 50 micron dopamine elicited cyclic AMP levels 524% of control values in the bovine ganglion, but only 152% in the feline ganglion (a value which is not statistically significant). Incubation with 50 micron isoproterenol produced an increase of 356% of control values in the cow, but no increase in the cat. SIF cells were classified into two types by fluorescence histochemistry. The bovine ganglion contained 23.7% Type I (solitary) SIF cells, and 76.3% Type II (clustered) cells, whereas the feline ganglion contained 99.5% Type II cells. Thus the feline ganglion lacks both Type I SIF cells and a dopamine receptor-adenylate cyclase complex. On the basis of biochemical and morphological evidence, we hypothesize that the Type I SIF cell is an interneuron, and infer that the lack of a response to dopamine stimulation in the feline ganglion is caused by a scarcity of interneurons in this species.

Animals↗
PubMed1978

Entire colon aganglionosis, and extensive aganglionosis: analysis of 94 cases in Japan.

Incidence, sex distribution, length of the involved bowel, associated malformations, treatment and operative results were analysed in 94 cases of entire colon aganglionosis, 87 of which were collected from 42 institutions in Japan and seven treated in our department. In this series, 62 were entire colon aganglionosis and 32 were extensive aganglionosis. Incidence of entire colon aganglionosis was four per cent of all aganglionosis seen, and that of extensive aganglionosis was two per cent. Male: female ratio was 2:1 in cases with entire colon aganglionosis and 1.3:1 in extensive aganglionosis. Associated malformation was rare in both of entire colon, or extensive aganglionosis. Of the 94 cases, 41 cases survived neonatal period, and cure was obtained in 23 of entire colon aganglionosis and three of extensive aganglionosis.

Colon↗
PubMed1978

Pharmacology of budralazine, a new antihypertensive drug.

Antihypertensive and pharmacological properties of budralazine were examined in comparison with other antihypertensive drugs. Budralazine was orally effective against various types of hypertension in rats and it, like reserpine but unlike hydralazine, produced a much greater pressure reduction in hypertensive than in normotensive rats. The drug was similar to reserpine and alpha-methyldopa but not to hydralazine in showing a gradually progressive action. At equihypotensive oral doses, budralazine was less potent than hydralazine in producing tachycardia in unrestrained SHR. After long-term therapy, it effectively prevented the development of hypertension in SHR to almost the same extent as did hydralazine. Budralazine failed to produce diuresis in SHR at antihypertensive doses but antagonized isolated rabbit aortic contractions induced by vasoconstrictors and decreased femoral arterial resistance in dogs. Thus, the antihypertensive budralazine is characterized by the ability to produce vasodilator, non-diuretic and weak cardiac stimulant effects.

Animals↗
PubMed1977

Evidence for dopamine-storing interneurons and paraneurons in rhesus monkey sympathetic ganglia.

In order to study and quantify the small, intensely fluorescent (SIF) cells and to examine their synaptology, the superior cervical sympathetic ganglia of rhesus monkeys were examined by a sequential glyoxylic acid (GA) monoamine fluorescence and electron microscopic technique. Correlated data concerning the sensitivity of the ganglia to dopamine were gathered by measuring the rise in cyclic AMP levels following incubation in vitro with exogenous dopamine. Cyclic AMP levels after incubation for 12 min with 50 micron dopamine showed marked increases, averaging 288% of control values. This indicates that these ganglia contain a dopamine receptor-adenylate cyclase complex. The number of SIF cells per mg of tissue was about half that found in the cow and rabbit, and only 1% of the number observed in the rat. Morphological data support the view that, in this species, there are almost equal numbers of type I (hypothesized interneuron) and type II (paraneuron) SIF cells. Presumptive SIF cell efferent synapses were observed by electron microscopy, the postsynaptic elements being dendritic spines or very fine nerve processes.

Animals↗