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Biomedical subjects

S K Hong

Publications and source records attributed to S K Hong.

At least 181 records · Page 10Linked to original sources
PubMed1985

Diving pattern of Tsushima male breath-hold divers (Katsugi).

The present study was undertaken to investigate the diving pattern, buoyancy-mass relationship, and some respiratory functions in professional male breath-hold divers in Tsushima Island, Japan. These divers always wear neoprene wet suits and use fins and 4-kg counterweights. They usually dive to 3-10 m depths. The rate of descent was 1.12 m/s for deeper dives (greater than 10 m), which is nearly twofold greater than that of Korean female divers also wearing wet suits and fins. However, the rate of ascent (0.8 m/s) was comparable to that of Korean women divers. On a typical summer day, they spend nearly 4 h in the water and perform 175 dives. The average dive and surface time were 39 and 42 s, respectively. The total bottom time was estimated to be 67 min/d, nearly twice that of Korean women divers. These divers do not adjust the counterweight and all are using a 4-kg weight. Nevertheless, the buoyancy-mass relationship revealed that they maintain the same degree of positive buoyancy (approximately 10% above the neutral level) at surface as do Korean women divers who adjust counterweights. The vital capacity was significantly greater in the diver than in the control (P less than 0.05), which was largely due to the greater expiratory reserve volume in the diver. The end-tidal O2 and CO2 pressures of the diver resting in air were not different from those of the control. These results indicate that, while the basic diving pattern is similar in both male and female breath-hold divers, the overall efficiency of diving (in terms of the rate of descent and the bottom time) appears to be superior in male divers.

Adult↗
PubMed1984

Photoaffinity labeling of organic anion transport system in proximal tubule.

The present investigation compares brush-border (BBM) and basolateral membrane (BLM) vesicles in terms of purity, function, appearance on sodium dodecyl sulfate (SDS) gels, and labeling pattern by use of N-(4-azido-2-nitrophenyl)-2-aminoethanesulfonic acid (NAP-taurine), a photoaffinity analogue of p-aminohippurate (PAH). Both BLM and BBM were vesicular by demonstration of PAH uptake into an osmotically active space and had probenecid-inhibitable uptake of PAH. Time courses for uptake were similar. 250 microM NAP-taurine resulted in a 35% inhibition of PAH uptake in BLM but it did not significantly effect PAH uptake into BBM. The latter was affected by 1 mM NAP-taurine. A comparison of Coomassie blue SDS gels of BLM and BBM showed markedly different staining patterns. A major band at approximately 52,000 daltons was more intensely stained in BLM than BBM. Major bands at approximately 40,000 and approximately 80,000 were stained more heavily in BBM than BLM. A minor protein at 26,000 in the BLM did not appear in BBM. An irreversible inhibition of PAH uptake in BLM was observed after photolysis in the presence of NAP-taurine. This was associated with the labeling of four protein bands on SDS polyacrylamide gels. In contrast no labeling was observed in BBM.

Affinity Labels↗
PubMed1984

Effect of high hydrostatic pressure on sodium transport across toad skin.

The short-circuit current (Isc) was measured as an index of active net sodium transport across the isolated toad skin under various hydrostatic pressures up to 300 ATA. Upon compression, the base-line Isc increased transiently during the first 10 min by 10-15 microA/cm2 (congruent to 20%) and then decreased continuously, leveling off at 40 min under pressure. The latter decrease in base-line Isc (P less than 0.05 at all pressures) was pressure dependent, and its magnitude was 30 microA/cm2 (60% inhibition) at 300 ATA. Similarly, the transepithelial electric potential difference (PD) tended to increase slightly during the early phase of compression and decreased during the steady-state phase of compression. The transepithelial resistance (R), calculated from PD/Isc ratios, generally increased under pressure. The addition of vasotocin to the inside bathing medium resulted in an increase in Isc and PD and a reduction in R at all pressures. The magnitude of peak Isc response to vasotocin was 50-60 microA/cm2 at pressures up to 100 ATA, but decreased to 30 microA/cm2 at 200-300 ATA (0.05 less than P less than 0.10 as compared to the response at 1 ATA). On the other hand the stimulatory effect of 1 mM cyclic adenosine monophosphate (cAMP), added to the inside bathing medium, on Isc was not affected by pressure between 1 and 300 ATA. From these results it is postulated that the inhibition of base-line Na transport under high hydrostatic pressure may be primarily due to a decrease in the outer membrane permeability to Na rather than an inhibition of the Na-K-ATPase.

Animals↗
PubMed1984

Responses of salt- and water-regulating hormones during a saturation dive to 31 ATA (SEADRAGON IV).

Four Japanese male subjects were studied during 3 days at 1 ATA, 3 days of compression to 31 ATA (1000 fsw), 14 days at 31 ATA, 12 days of decompression, and 3 days of postdive control at 1 ATA. The chamber was maintained at thermoneutral temperatures. During the 31-ATA exposure, urine flow increased about 500 ml/day (P less than 0.05) accompanied by an approximate 500-ml/day increase in osmotic clearance (Cosm) (P less than 0.05). Both urine flow and Cosm increases were primarily attributable to an increase in the overnight flow rates (P less than 0.01). The negative free water (-CH2O)/Cosm decreased during exposure to 31 ATA, indicating that a reduction in tubular water reabsorption may also contribute to the diuresis. Urine flow, Cosm, and -CH2O/Cosm all returned to predive values during decompression to 1 ATA. The urinary excretion rate of aldosterone increased from 2.7 +/- 0.3 micrograms/day at 1 ATA to 4.3 +/- 0.0 micrograms/day (P less than 0.01) at 31 ATA, remaining at about 3.8 micrograms/day until decompression. Urinary antidiuretic hormone (ADH) decreased from 50 +/- 7 to 33 +/- 3 mU/day (P less than 0.01) upon compression to 31 ATA and continued to decrease throughout the decompression phase. Plasma renin activity was increased by twofold (P less than 0.01) and plasma aldosterone by about 37% (NS) during exposure to 31 ATA. It is concluded that the reduction in ADH does not contribute significantly to the hyperbaric diuresis, and that the increased activity of the renin-angiotensin-aldosterone is a result of other postulated mechanisms resulting in an increased Cosm.

Adult↗
PubMed1984

Cardiovascular and renal responses to head-out water immersion in canine model.

Water immersion (WI) of anesthetized dogs to the midcervical level in the vertical sitting position under thermoneutral conditions (38 degrees C) leads to generalized increases in regional blood flows (radiolabeled microspheres) to most tissues. The increased flows can be accounted for by increased local VO2 in some tissues (heart, respiratory muscle), or by local heating (skin, fat). However, an alteration in the relation between cardiac output (Q) and VO2 appears to play a role in the large flow increments observed in skeletal muscle and abdominal viscera in WT. Studies of conscious, chronically instrumented dogs during 100 min of thermoneutral WI at 37 degrees C in the quadruped position indicate that both left atrial and aortic transmural distending pressures and left ventricular contractile performance (LV dP/dtmax) increase, while total peripheral resistance is unchanged. Cardiac output increases largely in association with an increase of heart rate. In addition, urine flow, sodium excretion, and osmolal clearance all increased. The cardiovascular adjustments occurred more rapidly than the renal responses. These results indicate that the conscious dog may be useful for investigation of physiological mechanisms involved in the WI response.

Abdomen↗
PubMed1983

Effects of gossypol on PAH transport in the rabbit kidney slice.

The present work was carried out to investigate if gossypol, a toxic weak organic acid (pK = 7.2) contained in cottonseed, is secreted by the renal proximal tubule through the organic anion transport system in the rabbit. The slice uptake of p-aminohippurate (PAH), a prototypical organic anion, was significantly inhibited (by 30%) only when the medium concentration of gossypol was raised to 10(-4) M. However, gossypol at the latter concentration also induced a 30% inhibition of the slice uptake of tetraethylammonium (TEA), a prototypical organic cation. Moreover, gossypol at 10(-4) M significantly decreased the slice oxygen consumption (congruent to 30%) and Mg-ATPase (70%) and Na-K-ATPase (90%) activities of renal cortical microsomes, while it significantly decreased the intracellular (K+). These results indicate that gossypol inhibits PAH uptake through nonspecific nephrotoxic effects on cell metabolism and Na-K-ATPase activity rather than through its specific interaction with the organic anion transport system.

Adenosine Triphosphatases↗
PubMed1983

Effect of temperature on the pH dependence of renal microsomal ATPase in the rabbit, rat and hamster.

The effects of temperature on the optimum pH of the renal microsomal Na-K-ATPase were studied in the rabbit, rat and hamster. The pH optimum of the ATPase in all three animals varied inversely with temperature, while a constant optimal OH-/H+ ratios were preserved at all temperatures. There appeared to be no difference between the Na-K-ATPase of the hibernating and non-hibernating representatives in terms of temperature dependence or substrate affinity. The pH optimum for the K-pNPPase activity was independent of temperature, indicating that the dephosphorylation step of Na-K-ATPase catalyzed reactions is not the source of the temperature dependence. These results are consistent with the Imidazole alphastat hypothesis of Reeves, which predicts that the optimal activity of the enzyme would occur at a constant pH-pKIM and thus a constant OH-/H+ ratio.

4-Nitrophenylphosphatase↗
PubMed1983

Effects of hypercapnia, hypoxia, and rebreathing on heart rate response during apnea.

Five series of breath-hold (BH) experiments were conducted on eight male subjects with the purpose of partitioning the effects of apnea per se, hypercapnia, and hypoxia on the development and maintenance of BH bradycardia. All BH were 90 s in duration and were achieved by face immersion at room temperature. Of the five series of BH, one was a continuous BH and the remaining included rebreathing at 15-s intervals while the face remained immersed. Comparison of heart rate (HR) responses between the continuous BH with air and that interrupted every 15 s by rebreathing without improving the alveolar gas composition yields the attenuating effect of respiratory activity. The hypercapnic effect was calculated from the difference in HR responses between two series of BH with O2, in which hypoxia was not present and rebreathing was common to both; in one rebreathing was through a CO2 scrubber thus creating different alveolar CO2 levels in the two series. The effect of hypoxia was deduced by finding the difference between the total bradycardial response (continuous BH) and the summed effects of hypercapnia and apnea per se. By this procedure, it was found that apnea and hypoxia reduced the HR by 19 and 18%, respectively, from the pre-BH value, and hypercapnia increased HR by 6% from the pre-BH level, thus accounting for the total 31% reduction in HR in a continuous BH.

Adult↗
PubMed1983

Effects of hypercapnia, hypoxia, and rebreathing on circulatory response to apnea.

Cardiovascular responses to cessation of respiration and to progressive hypoxia and hypercapnia were investigated noninvasively in eight male volunteers. A total of five 90-s breath holds (BH) with face immersion were performed by each subject. A continuous BH (BH-1) eliminated the circulatory effects of respiratory movements, BH with air (BH-3) or with O2 (BH-5) with rebreathing at 15-s intervals through a CO2 scrubber reduced the effect of hypercapnia, and BH with air (BH-2) or with O2 (BH-4) with rebreathing at 15-s intervals bypassing the CO2 scrubber produced hypercapnia with or without concomitant hypoxia. Mean arterial blood pressure rose continuously in BH-1 and BH-2 and to a much lesser degree in other BHs. Vasoconstriction was evident within 30 s of BH. Determined by impedance cardiograph, stroke volume (SV) rose by 33%, which was balanced out by a 30% reduction in heart rate (HR) from the pre-BH values, at the end of a continuous BH. A transient depression of cardiac output (CO) was observed at 30 and 60 s of BH-1. CO values were maintained at pre-BH levels throughout the BHs where progressive hypercapnia occurred (BH-2 and BH-4) but were depressed to a similar degree as BH-1 when hypercapnia was prevented (BH-3 and BH-5). Alveolar CO2 levels were found to be correlated linearly and positively with SV, HR, and CO. No such relationship existed between alveolar O2 levels and these hemodynamic parameters. Thus rebreathing and hypercapnia during BH prevented CO from falling during BH. It is reasoned that hypercapnia and consequent acidosis, through enhanced sympathoadrenal release of catecholamines, was responsible for the compensatory SV response.

Adult↗
PubMed1983

Energetics of wet-suit diving in Korean women breath-hold divers.

Contemporary Korean women divers wear wet suits during diving work to avoid the cold water stress. The present study was undertaken to evaluate the effect of wearing wet suits on the daily thermal balance of divers and on the duration of diving work. Rectal (TR) and skin temperatures and O2 consumption (VO2) were measured in four divers before and during diving work in summer (22.5 degrees C water) and winter (10 degrees C water). Subjects wore either wet suits (protected) or cotton suits (unprotected) for comparison. TR decreased 0.4 degrees C in summer and 0.6 degrees C in winter after 2 h of diving work in protected divers, while it decreased to 35 degrees C in 60 min in summer and in 30 min in winter in unprotected divers. Mean skin temperature of protected divers decreased to 31 degrees C in summer and 28 degrees C in winter, while that of unprotected divers decreased to 24 degrees C in summer and 13 degrees C in winter. VO2 toward the end of the diving work period increased by 80 (summer) and 140% (winter) in protected divers and by 160 (summer) and 250% (winter) in unprotected divers. From these values total thermal cost of diving work was estimated to be 260 and 370 kcal . day-1 in summer and winter, respectively.

Adult↗
PubMed1983

Time course of deacclimatization to cold water immersion in Korean women divers.

Seasonal basal metabolic rates (BMR), critical water temperature (Tcw), maximal body insulations (Imax), and finger blood flow during hand immersion in 6 degrees C water (Q finger) were measured periodically during the course of a 3-yr longitudinal study (1980-1982) of modern Korean diving women (ama), who have been wearing wet suits since 1977 to avoid cold stress during work. Methods and protocols were identical to previous studies of cotton-suited ama from 1961-1974. The BMR of modern ama did not undergo seasonal fluctuation (1980-1981) and was within the DuBois standard and comparable to nondivers year around Tcw of ama was still reduced by 2-3 degrees C in 1980 but increased progressively to equal that of nondivers in 1982, when compared at comparable subcutaneous fat thickness (SFT). Since modern ama and nondivers have 2.4 times thicker SFT (i.e., 4-13 mm) than in 1962 the absolute Tcw is significantly reduced. Q finger of ama was also significantly lower than controls in 1980 but in 1981-1982 was identical to controls. Imax of modern ama was identical to controls of comparable SFT in 1980-1982. The time course of cold deacclimatization thus was BMR, 3 yr; Imax, 3 yr; Q finger, 4 yr; and Tcw, 5 yr. This longitudinal study provides further evidence that acclimatization to cold did at one time exist in these diving women.

Acclimatization↗
PubMed1983

Triphenylmethylphosphonium (TPMP+) as a probe for peritubular membrane potential in the kidney slice.

The present work was undertaken to assess the validity of the use of TPMP+, a lipophilic cation, as a basolateral membrane-potential probe in the rabbit kidney slice. Cortical slices incubated in media containing 3H-TPMP+ reached an equilibrium slice/medium concentration ratio (S/M) for TPMP+ after 90 min. The equilibrium S/M TPMP+ was approximately 20 at TPMP+ concentrations between 30 and 50 microM. Concentrations of TPMP+ above 50 microM resulted in changes in tissue electrolytes and O2 consumption. Anaerobic incubation of slices in the presence of iodoacetamide decreased the S/M TPMP to approximately 3. When medium K+ was progressively increased, the S/M TPMP+ decreased continuously. There was a linear correlation between cell water/medium concentration ratios (C/M) for TPMP+ and K+ (r = 0.629, P less than 0.01). However, the C/M TPMP+ was 29.0 even at C/M K+ of 1.0, strongly suggesting the presence of a tissue binding component for TPMP+. When corrections are made for the above binding, the average C/M TPMP+ in slices incubated in the normal medium was approximately 13, equivalent to a Nernst potential of -64 mV. This value compared favorably to -54.3 mV obtained by microelectrodes in slices treated in the same fashion. It is concluded that the C/M TPMP+ corrected for binding may be used as a measure of the basolateral membrane potential in the steady state.

Animals↗
PubMed1983

Patterns of wet suit diving in Korean women breath-hold divers.

Work shifts, diving pattern, diving lung volumes, and counterweights were studied in professional Korean women breath-hold divers wearing wet suits. One of the major differences, compared with their diving pattern only a few years ago when wearing cotton suits, is the prolongation of the diving shifts from 70 to 180 min in the summer and 10 to 120 min in the winter. In sustained diving the average dive and surface times in a 5-m dive are 32 and 46 s, and in a 10-m dives, 43 and 85 s, respectively. During a 3-h shift the total bottom time for harvesting is 37 min in 5-m dives and 17 min in 10-m dives. Rates of descent and ascent are 0.55 and 0.84 m/s. The wet suit divers adjust their counterweights to obtain a 12% positive buoyancy at the surface of sea water in contrast to the 8% positive buoyancy of cotton suit divers. The average lung volumes before and after a dive are 79% and 64% of their vital capacities, values similar to those of previous cotton suit divers.

Adaptation, Physiological↗
PubMed1981

Renal transport of NAP-taurine.

The renal transport of N-(4-azido-2-nitrophenyl)-2-aminoethylsulfonate (NAP-taurine), a potential photoaffinity label, was studied using the rabbit renal cortical slice and the isolated perfused rat kidney. NAP-taurine inhibited the slice accumulation of PAH in a dose-dependent manner (ID50 = 2.5 X 10(-5) M). It accumulated to a steady-state slice-to-medium concentration ratio of 14. However, NAP-taurine was not toxic to the tissue, as it did not influence the accumulation of the organic cation tetraethylammonium. NAP-taurine transport was saturable and its accumulation was inhibited by the metabolic inhibitors PAH, probenecid, 4,4'-diisothiocyano-2,2'-disulfonic stilbene (DIDS), ouabain, and the absence of sodium. Kinetic studies showed that the Km for NAP-taurine is 3.5 X 10(-5) M, and also that PAH competitively inhibits NAP-taurine influx with a Ki of 1.2 X 10(-3) M. Experiments with the rat isolated perfused kidney gave the NAP-taurine-to-inulin clearance ratio of approximately 5, indicating net tubular secretion. DIDS significantly reduced this clearance ratio to 0.8. The results suggest NAP-taurine is handled by the kidney in a manner analogous to PAH and may thus be useful as a photoaffinity label for the renal organic anion transport system.

Affinity Labels↗
PubMed1981

Method for separation of cells and suspending medium at high pressure.

We describe a pressure chamber designed for measuring fluxes and equilibrium distributions of substances between cells in suspension and the extracellular medium at pressures up to 400 ATA. The pressure chamber contains a filtration apparatus capable of taking four separate samples of cell-free medium from a cell suspension at timed intervals, without necessity of decompression. In addition, a high pressure injection system makes possible the addition to a cell suspension of precise quantities of agents such as ionophores or metabolic inhibitors, for observations of their effects on cell functions at pressure. The chamber of filtration apparatus functioned successfully in preliminary experiments designed to measure the equilibrium distribution of 36Cl- in human erythrocytes at high pressure.

Atmospheric Pressure↗
PubMed1981

Suppressed renin release during hyperoxia in the conscious dog.

Recent studies have documented a marked inhibition of renal prostaglandin E2 excretion during hyperbaric oxygenation (HBO) in the conscious dog. Numerous other studies have shown that pharmacological inhibition of prostaglandin synthesis is associated with diminished renin release. The current experiments were designed to test whether HBO is also accompanied by reduced renin secretory rate (RSR) in conscious dogs. Dogs were implanted with electromagnetic flow probes on the left renal artery as well as with chronic arterial and renal venous catheters. Renal blood flow, peripheral plasma renin activity, and renal venous renin activity were measured, which allowed calculation of RSR for the left kidney. The dogs were studied at normal atmospheric pressure while breathing room air, followed by exposure to 100% oxygen at 2 or 3 ATA. The dogs were then returned to room air. The RSR decreased from 153.6 +/- 51.6 (ng . h-1) . min-1 to 72 +/- 21 (ng . h-1) . min-1 during HBO. Upon return to normoxia, RSR rose to 345 +/- 140.4 (ng . h-1) . min-1. This renin response to HBO seems best related to the previously documented inhibition of renal prostaglandin synthesis. These experiments provide nonpharmacological evidence that there may be a functional relationship between the renin-angiotensin system and renal prostaglandin release in awake animals.

Animals↗