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Biomedical subjects

T Endo

Publications and source records attributed to T Endo.

At least 1,153 records · Page 64Linked to original sources
PubMed1977

Presynaptic receptor systems on the noradrenergic neurones of the rabbit pulmonary artery.

A search was performed for presynaptic, release-modulating receptor systems on the post-ganglionic sympathetic nerves of rabbit pulmonary artery. Strips of the artery were preincubated with (-)-3H-noradrenaline and then superfused and stimulated transmurally. 1. Tetrodotoxin, guanethidine, and omission of calcium all suppressed the stimulation-evoked overflow of tritium, thus confirming selective release from noradrenergic neurones. 49% of the stimulation-evoked overflow of total consisted of 3H-noradrenaline, 22% of 3H-3,4-dihydroxyphenyglycol (DOPEG), and 9% of 3H-normetanephrine. Cocaine virtually abolished the evoked overflow of 3H-DOPEG; further addition of corticosterone also abolished that of 3H-normetanephrine. In the presence of cocaine plus corticosterone, unmetabolized 3H-noradrenaline accounted for 86% of the stimulation-evoked overflow of total tritium. The overflow evoked per pulse was 2.2 X 10(-5) of the tritium content of the tissue (1 Hz); it increased 2-fold when the frequency was raised to 8 Hz. 2. Presynaptic alpha-adrenoceptors have previously been demonstrated in this tissue (Starke et al., 1975b). High concentrations of isoprenaline reduced the stimulation-evoked overflow of tritium, presumably by alpha-adrenergic inhibiton. No presynaptic effect of up to 10(-5) M normetanephrine and metanephrine was found. 3. Dopamine slightly diminished the stimulation-evoked overflow of tritium, but only at 100 times the inhibitory threshold concentration of noradrenaline (which is 10(-8) M; Starke et al., 1975b), probably through activation of presynaptic alpha-adrenoceptors. Apomorphine failed to reduce the evoked overflow whether the superfusion medium contained cocaine and corticosterone or not. 4. Isoprenaline (10(-9) -10(-6) M) did not change the evoked overflow whether the medium contained cocaine and corticosterone or not, and whether the frequency was 1 or 2 Hz. Propranolol also had no effect. 5. Angiotensin II increased the stimulation-evoked overflow both in the absence and in the presence of cocaine and corticosterone. Equieffective concentrations of angiotensin I were 10 times higher. Saralasin had no effect, whereas 1-Sar,8-Ile-angiotensin produced a small increase. Both of the latter peptides behaved as presynaptic antagonists of angiotensin II. A presynaptically supramaximal concentration of the alpha-adrenergic agonist oxymetazoline prevented the facilitatory action of yohimbine, but not that of angiotensin II. Separation of 3H-compounds showed that angiotensin II caused a proportionate increase in stimulation-evoked overflow of 3H-noradrenaline, 3H-DOPEG, and 3H-normetanephrine; this finding rules out any inhibition of noradrenaline uptake mechanisms. 6. 10(-4) -10(-3) M acetylcholine caused hexamethonium-sensitive acceleration of basal tritium outflow. Much lower concentrations (10(-7) M and higher) reduced the overflow evoked by electrical stimulation. The evoked overflow of 3H-noradrenaline, 3H-DOPEG, and 3H-normetanephrine was proportionately decreased...

Acetylcholine↗
PubMed1976

Enkephalin: a potential modulator of noradrenaline release in rat brain.

In slices of rat occipital cortex preincubated with 3H-noradrenaline, methioine-enkephalin diminished the overflow of tritium evoked by electrical field stimulation or by 20 mM potassium. The effect was not modified by phentolamine, but was antagonized by naloxone. Giver alone, naloxone slightly increased the potassium-evoked overflow. It is concluded that enkephalin reduces transmitter release from cerebrocortical noradrenergic nerve endings. One-function of endogenous opiate receptor ligands may be presynaptic inhibition of central noradrenergic transmission.

Animals↗
PubMed1976

Deisovalerylblastmycin produced by Streptomyces SP.

A new antifungal antibiotic was isolated from the fermentation broth of Streptomyces sp. 5140-A1. Degradation studies of the crystalline antibiotic, m.p. 186 approximately 188 degrees C, C21H28O8N2, suggested Piricularia oryzae and less toxicity against killfish than antimycin A--blastmycin antibiotics.

Animals↗