Physiological, Pharmacological and Toxicological Implications of Heterodimeric Amino Acid Transportes

Kanai, Yoshikatsu,Endou, Hitoshi The Korean Physiological Society and The Korean So 2004 The Korean Journal of Physiology & Pharmacology Vol.8 No.3

Plasma Secretin Concentrations in Fasting and Postprandial States of Normal Korean Subjects

심여림,조양혁,심상수,남상채,김명석,Sim, Yeo-Rim,Jo, Yang-Hyeok,Sim, Sang-Soo,Nam, Sang-Chae,Kim, Myung-Suk The Korean Physiological Society 1985 대한생리학회지 Vol.19 No.2

한국의 정상 성인 20 명에서 공복시 및 음식물 섭취후의 철장 secretin농도를 방사면역 측정법(radioimmunoassay)으로 다음과 같이 측정하였다. 20명중 12명은 단백질 음식물인 햄버거와 쌀밥을 일주일 간격으로 섭취하였다. 햄버거 섭취 추 평균 혈장 secretin농도$(12{\sim}16\;pg/ml)$는 공복시의 평균 혈장 secretin농도(10 pg/m1 이하) 보다 유의하게 증가하였으며 그 증가가 오랫동안 지속하였다. 쌀밥의 섭취 후에는 혈장 secretin농도$(9{\sim}13\;pg/ml)$가 공복시의 값보다 증가하는 경향이었으며, 단지 식후 30분의 값에서만 유의하게 증가하였다. 식후 혈장 secretin농도의 증가폭은 햄버거에서의 증가 값이 쌀밥에서의 값보다 더 컸다. 나머지 8명은 자당 용액과 생리 식염수를 마셨다. 자당 용액의 섭취후 평균 혈장 secretin농도$(10{\sim}14\;pg/ml)$는 공복시의 값보다 유의하게 증가하였으나 쌀밥의 값과 마찬가지로 일시적이었다. 그러나 생리 식염수를 섭취한 후에는 혈장 secretin농도에 이렇다할 변화가 없었다. 이상의 결과로 미루어 정상 한국 성인에서는 단백질 음식물은 물론 탄수화물 음식물의 섭취로도 혈장 secretin농도가 증가한다고 사료된다. This study was conducted to investigate fasting plasma secretin and postprandial secretin concentrations after ingestion of a protein meal or a sucrose solution in 20 healthy Korean subjects. In 12 subjects, ingestion of a protein meal, hamburger resulted in a significant and sustained increase in the mean plasma secretin concentrations, from mean fasting levels of less than 10 pg/ml to $12{\sim}16\;pg/ml$, and the mean plasma secretin concentrations, $9{\sim}13\;pg/ml$, after a rice meal increased significantly but transiently compared with mean fasting levels. The magnitude of postprandial increase in the Plasma secretin concentration after the hamburger was greater than that of the rice meal. In the remaining 8 subjects, drinking of a sucrose solution resulted also in a significant but transient increase in the mean Plasma secretin concentrations, from mean fasting levels of less than 10 pg/ml to $10{\sim}14\;pg/ml$ which were significantly greater than that after a physiological saline. Significant increase in the plasma secretin concentration was not observed during the postprandial period after the physiological saline. It is inferred from the above results that the Plasma secretin levels increase significantly after ingestions of a carbohydrate meal as well as a protein meal in the Korean race.

Interaction between Cholecystokinin and Secretin in Isolated Rat Pancreatic Acini

Yoon, Shin-Hee,Hahn, Sang-June,Sim, Sang-Soo,Rhie, Duck-Joo,Song, In-Young,Baek, Hye-Jung,Kim, Myung-Suk,Jo, Yang-Hyeok The Korean Physiological Society 1995 대한생리학회지 Vol.29 No.2

A possible potentiation between cholecystokinin (CCK) and secretin in amylase secretion from isolated rat pancreatic acini was investigated. Combined treatment of acini with secretin and CCK at low concentrations, which are known to be physiological, resulted in enzyme secretion larger than the arithmetic sum of their separate effects. Such a potentiating effect also occurred between secretin and A23187 (Ca ionophore), between forskolin (adenylate cyclase activator) and CCK, and between forskolin and A23187. Staurosporin (protein kinase C inhibitor) and W7 (calmodulin antagonist) inhibited markedly the potentiated amylase release induced by the agonists, but KT5720 (protein kinase A inhibitor) did not affect the potentiated amylase release. Therefore, we concluded that the action of CCK in a physiological concentration is potentiated by secretin in a physiological concentration range and vice versa, and that the intracellular mechanism necessary for the potentiation is associated with $Ca^{2+}$. However, it is uncertain what mechanisms are involved in potentiation of amylase release after CAMP and $Ca^{2+}$.

Immunocytochemical Study on the Translocation Mechanism of Glucose Transporters by Insulin

Hah, Jong-Sik,Kim, Ku-Ja The Korean Physiological Society 1993 대한생리학회지 Vol.27 No.2

The mechanism of insulin action to increase glucose transport is attributed to glucose transporter translocation from intracellular storage pools to the plasma membrane in insulin-sensitive cells. The present study was designed to visualize the redistribution of the glucose transporter by means of an immunogold labelling method. Our data clearly show that glucose transporter molecules were visible by this method. According to the method this distribution of glucose transporters between cell surface and intracellular pool was different in adipocytes. The glucose transporter molecules were randomly distributed at the cell surface whereas the molecules at LDM were farmed as clusters. By insulin treatment the number of homogeneous random particles increased at the cell surface whereas the cluster forms decreased at the intracellular storage pools. It suggests that the active molecules needed to be evenly distributed far effective function and that the inactive molecules in storage pools gathered and termed clusters until being transferred to the plasma membrane.

Inhibition of Dicarboxylate Transport by p-chloromercuribenzoic Acid (PCMB) in Plasma Membrane Vesicles of Rabbit Proximal Tubule

Kim, Yong-Keun,Kim, Tae-In,Jung, Jin-Sup,Lee, Sang-Ho The Korean Physiological Society 1991 대한생리학회지 Vol.25 No.2

Effect of a sulfhydryl reagent, p-chloromercuribenzoic acid (PCMB), on the transport of succinate was studied in brush border (BBMV) and basolateral (BLMV) membrane vesicles isolated from rabbit renal cortex. PCMB induced an irreversible inhibition of the $Na^+-dependent$ succinate uptake in a dose-dependent manner with $IC_{50}$ of 55 and $65\;{\mu}M$ in BBMV and BLMV, respectively. The inhibitory effect of PCMB was prevented by a pretreatment of vesicles with dithiothreitol. PCMB did not increase $Na^+$ permeability at concentrations inhibiting succinate uptake. The PCMB inhibition of succinate uptake was due to a change in Vmax, but not in Km. When membrane vesicles were pretreated with PCMB in the presence of unlabelled succinate, the inhibitory effect was significantly reduced. In both BBMV and BLMV, succinate uptake was inhibited by various sulfhydryl reagents with the inhibitory potency of following order: $HgCl_2$>DTNB>PCMBS>PCMB. These results suggest that sulfhydryl groups are essential for dicarboxylate transport and that they may be located at or near substrate binding sites of the transporters in renal brush border and basolateral membranes.

Induction of Oscillatory Firing Activity by TTX in Rat Cerebellar Purkinje Cells

Seo, Wha-Sook The Korean Physiological Society 1995 대한생리학회지 Vol.29 No.1

Intracellular recordings were obtained from Purkinje cells in rat cerebellar slices maintained in vitro. Adding tetrodotoxin to the superfusion solution produced a typical pattern of repetitive burst firing consisting of a cluster of action potentials followed by a long hyperpolarization. TTX-induced oscillatory activity was not due to modulation of membrane potential although underlying mechanisms for maintenance of oscillatory activity were influenced by membrane voltage. The mechanism of TTX-induced oscillation was not related to the presence or amplitude of $I_h$ and could still induce the oscillatory activity after blockade of $I_h$ by cesium. The result from an experiment in which QX-314 was injected intracellularly strongly suggested that TTX-induced oscillatory firing activity was due to blockade of post-synaptic $Na^{+}$ currents intrinsic to PCs.

Overexpressed Mitochondrial Thioredoxin Protects PC12 Cells from Hydrogen Peroxide and Serum-deprivation

Lee, Yun-Song,Yu, Seung-A The Korean Physiological Society and The Korean So 2003 The Korean Journal of Physiology & Pharmacology Vol.7 No.1

Isolation and Characterization of Endosome Subpopulation in Chinese Hamster Ovarian Cells

Suh, Duk-Joon,Park, Mi-Yeon,Jung, Dong-Keun,Bae, Hae-Rahn The Korean Physiological Society 1996 대한생리학회지 Vol.30 No.2

Endosomes lower their internal pH by an ATP-driven proton pump, which is critical to dissociation of many receptor-ligand complexes, the first step in the intracellular sorting of internalized receptors and ligands. Endosomes are known to exhibit n great range of pH values that can vary between 5.0 and 7.0 within a single cell although the factors that regulate endosomal pH remain uncertain. To evaluate the morphological and topological differences of endosomes in the different stages, confocal microscopy was used. The early endosomes labeled with fluorescein isothiocyanate-dextran for 10 min at $37^{\circ}C$ were identifiable at the peripheral and tubule-vesicular endosome compartment. In contrast, the late endosomes formed by 10 min pulse and 20 min trace were located deeper in the cytoplasm and showed more vesicular features than early endosomes. For the purpose of determining whether ATP-dependent acidification was heterogeneous and whether the differences in acidification were attributed to differences in the activity of $Na^{+}-K^{+}$-ATPase and/or $Cl^{-}$ channel, endocytic compartments were fractionated into subpopulation using percoll gradient and measured ATP-dependent acidification. While all fractions exhibited ATP-dependent acidification activity, both the initial rate of acidification and extent of proton translocation were lower in early endosomes and gradually increased in late endosomes. Phosphorylation by PKA and ATP enhanced ATP-dependent acidification in both early and late endosomes, hut there was no difference in the degree of enhancement by phosphorylation between two subpopulations. When ATP-dependent acidification was determined in the presence or absence of vanadate ($Na_{3}VO_{4}$) or ouabain, only early endosomes exhibited the vanadate or ouabain dependent stimulation of acidification activity, suggesting the inhibition of $Na^{+}-K^{+}$-ATPase. Therefore, it seems probable that the inhibition of early endosome acidification by $Na^{+}-K^{+}$-ATPase observed in vitro at least in part plays a physiological role in controlling the acidification of early endosomes in vivo.

Characteristics of Synthesized Red Cells Using Bovine Hemoglobin as Oxygen Carrier

Cho, Eng-Haeng,Hah, Jong-Sik,Kim, Ku-Ja The Korean Physiological Society 1992 대한생리학회지 Vol.26 No.1

The encapsulation of the Purified bovine hemoglobin with Phospholipids obtained from egg folk was performed using a rotary vacuum evaporator. The prepared Hb-containing liposome (hemosome) had good properties as artificial red blood cell. The shape and size of the hemosomes were measured by a phase contrast microscope and image analyzer. The function of the hemosome as oxygen carrier was tested by measuring oxygen saturation curve with blood gas analyzer and infusing it into rats. The prepared hemosome was 1.184 + 0.423 ${\mu}m$ in diameter and round in shape. $P_{50}$ value of the hemosome solution was 28 mmHg. The synthesized red cells seem to function as oxygen carrier, because the severely bled rats were prolonged in their life by transfusion of the hemosome solution containing bovine hemoglobin.

Cardiovascular Neurons Mediating Somatosympathetic Reflex in Rostral Ventrolateral Medulla

Goo, Yong-Sook,Kim, Sang-Jeong,Kim, Jun,Sung, Ho-Kyung The Korean Physiological Society 1993 대한생리학회지 Vol.27 No.2

The rostral ventrolateral medulla (RVLM) includes vasopressor neurons, which transmit activation signals to the intermediolateral nucleus (IML) of the spinal cord, where the preganglionic sympathetic nucleus is located, to raise arterial blood pressure (BP). However, controversy exists as to the possible depressor area in the RVLM and the pathway involved. The present study persued evidence far the location of depressor neurons and the pathway by simultaneously observing changes in BP and the firing rate (FR) of cardiovascular neurons (CVNs) in the RVLM during the somatosympathetic reflex (SSR) elicited by peripheral nerve stimulation, since CVNs are known to contribute to the generation of the sympathetic nerve discharge. In 42 cats, anaesthetized with $\alpha-chloralose$, single unit recording was performed, using carbon filament electrodes inserted into the RVLM, enabling estimation of the post R wave unit histogram (PR-UNlT) and the spike triggered average of sympathetic nerve discharge (STA-SND), allowing identification of CVNs. Antidromic stimulation of spinal $T_2$ segment was followed to determine whether the identified CVN projects axonal endings to the spinal cord (reticulospinal neuron). The sciatic nerve was electrically stimulated at $A\delta-intensity$ (1 mA, 0.1 ms), 1 Hz and C-intensity (10 mA, 0.5 ms), 20 Hz to elicit the depressor, and pressor responses of the SSR, respectively. Simultaneous measurement of CVN firing rate was made. Experimental results are summarized as follows. 1) 20 out of 98 CVNs had axonal projections to the spinal cord and 17 out of 98 CVNs showed FR changes during SSR. 2) Response patterns of FR and BP during SSR were classified into 8 types. 3) These 8 different response patterns could be further classified into those from pressor and depressor neurons. These results demonstrate that some CVNs were identifiable as reticulospinal neurons responding to anti-dromic stimulation and that CVNs operating as depressor neurons as well as pressor neurons exist in the RVLM, both of which are involved with SSR mediation. Therefore, evidence was found that an independent depressor pathway might be involved in the mediation of SSR.