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K Suwa

Publications and source records attributed to K Suwa.

At least 109 records · Page 6Linked to original sources
PubMed1984

Effects of drug-induced reduction in oxyhemoglobin affinity on survival time of mice in severe hypoxic conditions.

We studied the effect of ortho-iodo sodium benzoate (OISB) given intraperitoneally to mice. 300 and 600 mg/kg of OISB increased P50 from the control value of 41.2 mmHg to 42.7 mmHg and 45.7 mmHg, respectively. The mice were then exposed to two experimental hypoxias, namely, hypobaric hypoxia and carbon monoxide hypoxia. Mean survival time was prolonged from 67.8 (control saline) to 94.8 sec (OISB 300 mg/kg) and 112.2 sec (OISB 600 mg/kg) in the hypobaric hypoxia, and from 201.3 sec (control saline) to 329.7 sec (OISB 300 mg/kg) and 407.7 sec (OISB 600 mg/kg) in the carbon monoxide hypoxia. We concluded that OISB had prolonged survival time by reducing oxyhemoglobin affinity, thus facilitating oxygen release in severe hypoxic conditions.

Animals↗
PubMed1984

Bioavailability of nalidixic acid from uncoated tablets in humans--Part I: Correlation with the dissolution rates of the tablets.

Bioavailabilities of three commercially available tablets and two trial tablets of nalidixic acid were determined. The correlation between in vivo bioavailability parameters and in vitro dissolution rates derived by eight methods (oscillating basket I and II, beaker I, II, and III, rotating basket, paddle and rotating flask) is discussed. Nalidixic acid and its metabolite, 7-hydroxynalidixic acid, were determined in serum by HPLC with a strong anion-exchange resin column. All parameters for nalidixic acid bioavailability showed significant differences among the tablets tested. The relationship between Cmax and AUC was not linear but concave. However, Cmax decreased linearly in proportion to the delay of Tmax. The rank order of tablets according to bioavailabilities was just the same as the rank order obtained when comparing dissolution rates determined by any of the above methods, with the exception of one tablet which had a poor disintegrating ability. The parameters for the rate of bioavailability (Cmax and Tmax) showed good linearity with 1/T50 determined by all of the methods. However, AUC showed significant correlation with neither T50 nor 1/T50.

Adult↗
PubMed1984

Bioavailability of Nalidixic acid from uncoated tablets in humans--Part II: Bioavailability in beagles and its correlation with bioavailability in humans and in vitro dissolution rates.

The bioavailability of nalidixic acid in beagles was determined using the same tablet formulations previously tested on humans and was compared with bioavailability in humans and with in vitro dissolution rates. The beagle bioavailability test provided lower power in all of the bioavailability parameters than did the human test. Tmax of the tablets did not greatly differ in beagles, although in humans a wide variation of Tmax was seen. A linearity between Cmax and AUC0-infinity was observed in beagles, but Tmax did not show a linearity with Cmax or AUC in dogs, which is quite different from the relations observed in humans. The rank order of tablets according to Cmax was exactly the same between humans and beagles. AUC also showed the same rank order between humans and beagles except for on tablet with a poor disintegrating ability. A significant correlation between human and beagle Cmax values was obtained (r = 0.8952; p less than 0.05), but not between human and beagle AUC and Tmax values.

Animals↗
PubMed1983

PaO2 and intratracheal pressure in oscillatory ventilation in experimental respiratory failure.

In order to study the effect of high frequency ventilation on the pulmonary gas exchange in respiratory failure, we measured the PaO2 and other pulmonary gas exchange parameters for ventilatory rates of 0.5, 1.2, 4.8, and 16 Hz in dogs, to which acute respiratory failure was created by intravenous infusion of oleic acid. Either the mean intratracheal pressure or the end-tidal intratracheal pressure was controlled. A loud-speaker ventilator of our own design was modified so as to enable variation of the intratracheal pressure. Ventilation was measured using an ultrasonic instrument which counts the number of turbulent eddies. The tidal volume was set slightly higher than that was determined for healthy animals, but the resulting PaCO2 values were consistently higher than normal when PaO2 values were low. With the mean intratracheal pressure kept constant at 5, 10, and 15 cm H2O, PaO2 values with the FIO2 of 1 were between 41 and 46 at mPit of 5, 65 and 82 at 10 cm H2O, 278 and 423 at 15 cm H2O. No increase in PaO2 was observed with the increase in respiratory frequencies. If anything, a slight reduction in PaO2 at 8 and 16 Hz was observed, though not statistically significant. With the end-tidal intratracheal pressure constant, PaO2 varied but again correlated well with the mPit.

Animals↗
PubMed1982

Effects of ortho-iodo-sodium benzoate (OISB) on oxygen-hemoglobin affinity and its relation to plasma concentrations in dogs.

Effects of ortho-iodo-sodium benzoate (OISB) on oxygen-hemoglobin affinity were studied in unanesthetized beagles with simultaneous measurement of its plasma concentrations. Oxygen-hemoglobin affinity changes correlated well with the plasma concentrations of the drug. Intravenous administration of 100 mg/kg of OISB increased P50 significantly from the control value of 28.6 +/- 0.8 mmHg to 29.5 +/- 0.7 mmHg and 30.0 +/- 0.5 mmHg, 5 min and 30 min after the infusion, respectively. P50 gradually decreased thereafter, and after 1 hr period, elevation was no longer significant. Administration of 200 mg/kg of OISB caused a significant increase in P50 from the control of 29.3 +/- 0.3 mmHg to 30.5 +/- 0.4 mmHg, 31.1 +/- 0.3 mmHg, 31.1 +/- 0.3 mmHg and 30.5 +/- 0.5 mmHg, at 5 min, 30 min, 1 hr and 3 hr, respectively. P50 elevation declined thereafter to control levels. Plasma concentrations of the drug reached its highest level 5 min after the administration and declined gradually thereafter. All significant elevations of P50 were accompanied by the plasma concentrations of the drug more than 200 micrograms/ml. Biological half-life of the drug was found to be about 5.5 hr.

Animals↗
PubMed1982

Ventilatory volume and pressure required for oscillatory ventilation in dogs.

We determined the ventilatory volume and pressure required to maintain a PaCO2 of 40 mmHg in dogs at between 0.5 and 16 Hz. The ventilator used was that incorporating a powerful, specially made loudspeaker to which a sine-wave signal was introduced. A windmill-type flowmeter measured the minute volume. The tidal volume, expressed per kg of body weight, was 16.1 at 0.5 Hz, decreasing linearly with log f, and reaching a value of 6.1 ml/kg at 16 Hz. The minute volume increased 10 times from 0.5 to 16 Hz. The intratracheal pressure was 12 to 13 cmH2O between 0.5 and 2 Hz, rising to 16 at 4 Hz and finally reaching 77.2 cmH2O at 16 Hz. The PaO2 values were always above 500 mmHg when FIO2 was 1.0. The frequency-impedence data were analyzed for R, I and C values. The fitting of the data to an R-I-C series model was good, but the R values obtained were considerably higher than those reported using a smaller amplitude of oscillation.

Animals↗