Search PubMed⌕ Search

Biomedical subjects

K Uchida

Publications and source records attributed to K Uchida.

At least 1,261 records · Page 70Linked to original sources
PubMed1987

Difference in the mode of acute cold-induced hypothermia between rat and hamster.

The present work was undertaken to elucidate the underlying causative factors limiting survival in hypothermic rats (non-hibernator) and hamsters (hibernator). A variety of physiological and biochemical parameters were measured for 28 male Wistar rats (205-286 g) and 26 male golden hamsters (85-118 g) before and during induction of hypothermia to colonic temperature (Tco) of 18 degrees C. With progressive decreases in Tco, parallel falls in VO2, VCO2, and heart rate were observed. In rats, plasma pH (pHp) in arterial blood was significantly lowered from 7.453 at Tco of 38 degrees C to 7.327 at Tco of 18 degrees C (p less than 0.001). From the observations of increased arterial PCO2 and bound CO2 (bicarbonate ion) concentration, together with the unchanged blood lactate, respiratory acidosis caused by hypoventilation was suggested to be responsible for the decrease in pHp. In contrast to rats, in hamsters pHp was almost unchanged during the induction of hypothermia, while nearly complete depletion of blood glucose (-84.6%) and liver glycogen (-99.5%) were observed when Tco of 38 degrees C was lowered to 18 degrees C. It is concluded that the decrease in pHp is a limiting factor for rats to survive the deep hypothermia at Tco of 18 degrees C and the exhaustion of carbohydrates as an energy supply for hamsters.

Animals↗
PubMed1987

A method for estimating contact time of red blood cells through lung capillary from O2 and CO2 concentrations in rebreathing air in man.

The gas exchange ratio (R) obtained from O2 and CO2 concentrations measured in rebreathing air usually shows a linear relation to the PCO2. By referring to this relation and the R which equals the Haldane effect coefficient and zero, the true- and oxygenated-venous PCO2 are obtained in addition to the alveolar PCO2. When these PCO2 are evaluated, the R-PCO2 line can also be computed theoretically from a numerical solution on the overall O2 and CO2 diffusions in the red blood cell. By comparing both the experimental and theoretical R-PCO2 lines with each other, we derived a contact time equation. Since the linear approximation of the R-PCO2 relation gave rise to an error in the contact time (tc), first a factor to correct the linearity of the R-PCO2 line was derived. Next, using these parameter values, tc was quantitatively determined from experimental data obtained during rebreathing in 5 normal subjects and it was compared with that estimated from the pulmonary diffusing capacity for CO in the same rebreathing experiment. When the extracellular HCO3- dehydration rate was taken to be 0.1 s in time constant, the tc, being ca. 0.7 and 0.4 s at rest and during exercise, respectively, showed good agreement with those obtained from the diffusing capacity for CO.

Capillaries↗
PubMed1987

Experimental analyses of pulmonary gas exchange in a standing position at rest and during treadmill exercise.

Quantitative relations between O2 uptake (Vo2), arterial-venous O2 content difference [a-v)CO2), and contact time (tc) were measured at rest and during exercise in 7 normal subjects, using a rebreathing technique. By injecting a known amount of pure O2 into a rebreathing circuit, the VO2 was measured from the time interval during which the injected O2 volume was consumed. From the O2 and CO2 concentrations in rebreathing air the gas exchange ratio (R), which was linearly related to the PCO2, was determined. By using the slope of the R-PCO2 relation, the (a-v)CO2 was evaluated from the slope of the CO2 dissociation curve between the true- and oxygenated-venous PCO2. These two venous PCO2 were estimated from the R-PCO2 relation by use of the Haldane effect coefficient and by extrapolating it to the abscissa, where R = O. Furthermore, tc was evaluated by inserting the above two venous PCO2 together with the alveolar PCO2 into a contact time equation. The mean (a-v)CO2 and tc had consistent relations to the VO2 and (a-v)CO2, respectively. (a-v)CO2 = 9.5 X VO2 0.35, (vol%), and tc = 4.86 X (a-v)CO2 -1.025, (s).

Adult↗
PubMed1987

Effect of atrial natriuretic factor on aldosterone and its precursor steroid production in adrenal zona glomerulosa cells from spontaneously hypertensive rats.

The effect of alpha-human atrial natriuretic factor (alpha-hANP, 10(-6) M- 10(-8) M) on basal, and maximum angiotensin II (AII, 4.8 X 10(-8) M)-, ACTH (4.3 X 10(-9) M)-, and potassium (8mM)-stimulated levels of corticosterone, 18-hydroxycorticosterone (18-OHB) and aldosterone production were studied in adrenal glomerulosa cells from spontaneously hypertensive rats (SHR) at 14 weeks of age as compared to those in the age-matched Wistar-Kyoto rats (WKY) on a normal sodium diet. Plasma corticosterone, 18-OHB and aldosterone levels and the aldosterone response in vitro to the graded doses of AII were similar in SHR and WKY. Basal, and maximum AII-, ACTH-, and potassium-stimulated levels of corticosterone, 18-OHB and aldosterone also were similar in the cells from SHR and WKY. alpha-hANP similarly inhibited basal and stimulated levels of these corticosteroids in the cells from SHR and WKY. These results indicate that the inhibitory effect of alpha-hANP on aldosteronogenesis is unaltered in SHR at 14 weeks of age on a normal sodium diet.

18-Hydroxycorticosterone↗
PubMed1987

Electron microscopic and cytochemical studies of the thrombocytes of the tortoise (Geoclemys reevesii).

The thrombocytes of the tortoise (Geoclemys reevesii) were studied at the electron microscopic level. The presence of a surface connected canalicular system, composed of numerous anastomosing canaliculi, has been demonstrated by the ruthenium red technique. However, monoamine storage organelles have not been found in tortoise thrombocytes. Peroxidase activity is localised to the nuclear envelope and the rough surfaced endoplasmic reticulum, but is not present in the Golgi apparatus or granules. Acid phosphatase is localised to the large inclusions with myelin bodies, but is not found in the electron-lucent small granules. These results are discussed in relation to those from comparable studies of mammalian and submammalian thrombocytes.

Acid Phosphatase↗