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Biomedical subjects

H Higashino

Publications and source records attributed to H Higashino.

82 records · Page 5Linked to original sources
PubMed1979

[Effects of orciprenaline on the responses to Ca, K, acetylcholine and Ba in the isolated seminal vesicles of guinea pigs, especially in relation to cyclic AMP (author's transl)].

By using the isolated seminal vesicles of guinea pigs, the effects of dibutyryl cyclic AMP and beta-stimulant, orciprenaline, on the responses to Ca, K, acetylcholine and Ba were investigated, especially in relation to cyclic AMP. The following results were obtained. 1. Orciprenaline inhibited the contraction produced by Ca, K, acetylcholine and Ba in a dose-dependent manner, and the inhibition became larger in the order of Ca, K, acetylcholine and Ba. 2. Dibutyryl cyclic AMP showed the same results as those of orciprenaline. That is, dibutyryl cyclic AMP inhibited the contractions produced by acetylcholine and Ba. 3. Orciprenaline showed the increased level of cyclic AMP in a dose-dependent manner. But the increase was not remarkable in the concentration in which the contractions produced by the tested contractile agents were inhibited by about 50%. From these results, the following suggestions were obtained; (1) there exists beta-receptor in guinea pig seminal vesicles and (2) a part of actions of orciprenaline is due to a mechanism unrelated to cyclic AMP.

Acetylcholine↗
PubMed1976

Biological activity of synthetic corticotrophin with short chain lengths in the rabbit.

The andrenocorticotrophic effect of a synthetic substituted adrenocorticortophic hormone (ACTH), alpha-1-18NH2-D-Ser1-Lys17, 18-ACTH (CIBA 47, 795-Ba) has been compared with that of alpha1-24-ACTH (tetracosactide), alpha1-24-ACTH depot (tetracosactide depot) and alpha1-18NH2-Gly1-ACTH (giractide) in the rabbit. Plasma corticosteroid levels after salin injection were higher in the afternoon than in the morning. The highest value was observed at 3 p.m. 41,795-Ba, either given intravenously or intramuscularly, was shown to be the most potent peptide followed by tetrocosactide depot and was 15 times more potent than tetracosactide and giractide in steroidogenic activity in the rabbit. The intravenous administration of 41,795-Ba caused more sustained stimulation of the adrenal cortex than the intramuscular injection. These results reveal the diurnal variation pattern of the pitutitary-adrenal axis of the rabbit similar to that of the rat and also confirm the finding that alpha1-18NH2-Dser1-Lys17, 18-ACTH is a potent adrenocorticotrophic peptide without the addition of any agent to delay its absorption in the rabbit.

Adrenal Cortex Hormones↗
PubMedDate not supplied

Tissue variation of acute haemodynamic changes by NG-nitro-L-arginine in stroke-prone spontaneously hypertensive and Wistar-Kyoto rats.

1. The acute effects of nitric oxide synthase inhibition on the haemodynamics in stroke-prone spontaneously hypertensive (SHRSP) and normotensive Wistar-Kyoto (WKY) rats were investigated using radiolabelled microspheres. 2. Intravenous administration of 3 and 6 mg/kg NG-nitro-L-arginine (L-NNA) caused a significant increase in total peripheral resistance, a decrease in cardiac output and an increase in blood pressure in both SHRSP and WKY rats. 3. Significant decreases in regional blood flow (RBF) in the lung, muscle and stomach of WKY rats were observed following L-NNA administration. 4. NG-nitro-L-arginine produced a 70% increase in brain regional blood flow at a dose of 6 mg/kg only in SHRSP. 5. There was a variation in the involvement of nitric oxide (NO) in different tissues. 6. It is concluded that hypertension in SHRSP augments NO-mediated vasodilation.

Animals↗
PubMedDate not supplied

Validity of microsphere model in cerebral blood flow measurement using N-isopropyl-p-(I-123) iodoamphetamine.

A microsphere model is sometimes used when calculating cerebral blood flow (CBF) using N-isopropyl-p-[I-123]iodoamphetamine (IMP), and is based on the assumption that there is essentially no washout of IMP. The validity of a microsphere model was investigated by comparison with the values of CBF obtained by means of a model which takes into consideration the diffusion of IMP from brain tissue to blood (nonmicrosphere model). When calculating CBF by the latter model, the look-up table method was used with expression of the double integral in the model equation by the recursion relations, a method which is useful for obtaining pixel-by-pixel values. The average rate constants for diffusion from brain to blood of gray and white matter were 0.021 and 0.0016 min-1, respectively. The values of CBF obtained by applying a microsphere model to the data acquired from 0 to 3.2 min after IMP injection were overestimated by approximately 23% compared with those values obtained using a nonmicrosphere model. This is considered to be due to the effect of the IMP activity in the vascular space. Values obtained using the data acquired from 3.2 to 6.4 min were underestimated by approximately 15%. When the values of CBF obtained by a microsphere model were interpolated, they became nearly equal to those obtained using a nonmicrosphere model at about 4 to 5 min after injection. This is suggested to be the reason why the underestimation due to diffusion from brain to blood is cancelled out by the overestimation due to the IMP in the vascular space. Our preliminary results suggest that it is necessary to take the diffusion of IMP from brain tissue to blood into account for the quantification of CBF using IMP.

Amphetamines↗
PubMedDate not supplied

Cadmium effect on the Na,K-ATPase system in cultured vascular smooth muscle cells.

The present study focuses on the interaction between cadmium (Cd) and the Na, K-ATPase system in in vitro grown vascular smooth muscle cells (VSMCs) derived from the rat carotid artery. In disrupted VSMCs rendered permeable by osmotic shock, Cd inhibited Na, K-ATPase; I50 was reached at 10(-5) M Cd. Mg-ATPase was also inhibited by Cd; I50 was attained at concentrations of 10(-4) M Cd. Cd inhibition of Na,K-ATPase in the VSMCs was noncompetitive with respect to Na, K, and ATP. Rubidium transport experiments performed with intact VSMCs demonstrated that within an incubation period of 150 minutes, a concentration of 10(-4) M Cd in the extracellular fluid exerted no acute effect on the Na-K pump. Within this time interval, intracellular Cd attained a concentration eightfold higher than the extracellular Cd concentration. Thus, it appears that under acute conditions Cd exerts its inhibitory effect on Na, K-ATPase only in disrupted VSMCs. The data further suggest that, in the VSMC, conditions under which Cd inhibits Na, K-ATPase are consistent with inhibition from the cytoplasmic side of the cell membrane.

Animals↗
PubMedDate not supplied

Optimum branched-chain amino acids concentration for improving protein catabolism in severely stressed rats.

In this study, an experiment was performed to investigate the optimal concentration of branched chain amino acid (BCAA) in hyperalimentation to be administered when protein catabolism is accelerated by sepsis or bodily injury. Amino acid solutions containing BCAA 25%, 30%, 40%, 45% and 50% were prepared and were administered iv for three days with other essential amino acid-containing nitrogen in the same volume into rats with peritonitis which had been developed by ligature and puncture at the cecum, and the results were compared. After observing for three days, the influence over nitrogen balance, improvement of 3-methyl-histidine/creatinine in urine, weight loss in muscles, and aminogram in serum and muscles indicated that the hyperalimentation under stress is utilized most effectively when amino acid contains 45% of branched-chain amino acid.

Amino Acids, Branched-Chain↗
PubMedDate not supplied

Physiological characteristics of diabetic neuropathy in sucrose-fed Otsuka Long-Evans Tokushima fatty rats.

Diabetic neuropathy is a very common complication of diabetes mellitus, and animal studies have contributed tremendously to its understanding. The aim of this study was to estimate the neuropathic alterations in the Otsuka Long-Evans Tokushima fatty (OLETF) rats, an animal model of human type 2 diabetes mellitus. For this purpose, four groups of animals were used: untreated OLETF rats, sucrose-fed for 2 months OLETF rats, untreated Long-Evans Tokushima Otsuka (LETO) nondiabetic rats as genetic controls of OLETF, and sucrose-fed LETO rats. All were examined at baseline, at the end of the sucrose treatment, and during a washout period. The following parameters were evaluated: motor nerve conduction velocity (MNCV), sensitivity to noxious thermal and mechanical stimuli using the tail-flick (TF) and tail-pressure (TP) tests, and blood glucose (BG) and HbA1c levels. Our results showed that BG and HbA1c were significantly higher in OLETF rats when compared with those in control LETO rats. Sucrose caused remarkable increase of BG and HbA1c in the OLETF rats, but not in the sucrose-fed LETO rats. MNCV and thermal nociception significantly decreased in OLETF rats in their 10th month, while the values of the TP test did not differ compared with those from LETO rats. Sucrose administration significantly decreased the MNCV, and increased the pain threshold evaluated by the TF and TP tests, compared with those in the control OLETF rats. The studied parameters were not significantly altered in sucrose-fed LETO rats. In conclusion, our findings show that signs of diabetic neuropathy appear late in the individual development of the OLETF rats, and MNCV and thermal nociception are selectively affected in this strain. Sucrose deteriorated the diabetic state, decreased MNCV, and caused thermal and mechanical hypoalgesia.

Animals↗
PubMedDate not supplied

Endotoxin clearance through whole body rinse out in relation to histologic integrity in the rat.

The effects of normothermic whole body rinse out (NWBRO) with FC-43 perfluorocarbon emulsion on the course of endotoxic shock were examined in male Wistar rats. These animals, conscious and unrestrained, were infused over 10 min with 60 mg/kg of E. coli endotoxin (LD100) and observed for 6 hr. The rats developed hypotension, plasma extravasation, metabolic acidosis, increase in serum GPT and GOT, and extensive hemorrhages in the small intestine. Another group of rats was subjected to blood substitution with FC-43 emulsion (artificial blood) 30 min after endotoxin infusion, until the hematocrit dropped to less than 3%, after which 6-9 ml of donor blood was exchange transfused with the emulsion. NWBRO caused a transitory rise in the GOT level, but more importantly it resulted in 98% endotoxin clearance, improved blood alkaline reserves, trimmed elevated GPT and GOT levels, and attenuated hemorrhage and epithelial necrosis in the small intestine.

Alanine Transaminase↗