DISCUSSION Acute regulation of sodium pump activity There is a burgeoning literature on mechanisms responsible for short term regulation of Na,K-ATPase activity (Aperia et al, 1996, 1994; Boron et al, 1997; Bertorello & Katz, 1993). Pathways linked to both generation of protein kinase C (PKC) and/or cyclic-AMP dependent protein kinase A are postulated to regulate Na,K-ATPase activity by changing the alpha catalytic subunit phosphorylation status. However, phosphorylation has been associated with both decreased activity (Aperia et al, 1994; Chibalin et al, 1995; Middleton et al, 1993; Satoh et al, 1993a, 1993b), and increased activity (Carranza et al, 1996a, 1996b), and no change in activity (Boron et al, 1997). There is also evidence that PKC causes a withdrawal of sodiuln pumps from the basolateral membranes even if there is mutation of the phosphorylation site (Boron et al, 1997). Proximal tubule Na,K-ATPase activity is also inhibited (whether directly or indirectly is not known) by activation of phospholipase A2 which stimulates production of arachidonate metabolites of cytochrome P-450 such as 20-HETE (Aperia et al, 1996; Nowicki et al, 1997; Ominato et al, 1996). Although the precise signaling mechanisms re main to be elucidated for the responses to altered blood pressure, our results indicate that the inhibition of the sodium pump activity in PT is due to structural modification of the pump itself or an associated regulator, rather than solely mediated by trafficking of active pumps to a new location, because the data demonstrate. significant changes in total ATPase activity that persist through membrane fractionation and phase partitioning, and our results implicate a role of cat P45O aa metabolism to 20-HETE in the response(Zhang et al, 1998) Altered natriuretic responses in hypertension As discussed in the introduction, an altered natriuretic response to an elevation in blood pressure is the hallmark of hypertension. The Spontaneously Hypertensive Rat (SHR)has numerous renal defects that could account for the development of hypertension. In regards to this project, the PT of SHR fail to respond normally to the natriuretic hormone dopamine (Kinoshita et al, 1989), and they have enhanced tubuloglomerular feedback (TGF) response (reviewed in Cowley & Roman, 1997). Our results indicate a distribution of apical sodium transportes in SHR is the same as in acutely hypertensive SD (Magyar et al, 1997), In summary, our findings to date suggest that the dynamic regulation of proximal tubule and loop of Henle sodium transport by fluctuations in blood pressure may be mediated by changes in sodium transporter characteristics at both the apical and basolateral membranes: 1) by reversible inhibition of basolateral Na,K-ATPase activity in the PT and activation in the TALH, and 2) relocation of a set of apical proteins, including NHE-3 and NaPi, consistent with redistribution to intermicrovillar cleft region and/or internalization to endosomal pools in the PT. The reciprocal modulation of Na,K-ATPase activity in PT and TALH contributes the driving force for activating TGF, while minimizing changes in delivery of salt and water to the hormone sensitive distal nephron.
Adenosine Triphosphatases ; Animals ; Blood Pressure ; Boron ; Catalytic Domain ; Cats ; Cyclic AMP-Dependent Protein Kinases ; Cytochrome P-450 Enzyme System ; Dopamine ; Hypertension* ; Loop of Henle ; Membranes ; Metabolism ; Nephrons* ; Phospholipases A2 ; Phosphorylation ; Protein Kinase C ; Rats, Inbred SHR ; Sodium ; Sodium-Potassium-Exchanging ATPase

OBJECTIVETo observe the effect of salvianolic acid B (SalB) on high energy phosphate and activity of ATPase of cerebral ischemia in mice, and to study the role of SalB on hydrocephalus further.

METHODNIH mice were divided into four groups randomly: Sham-operated group, cerebral ischemia group, SalB-treated group and Nimodipine (Nim)-collated group. In Sal B-treated group, mice were injected with SalB (22.5 mg x kg(-1)) in vena caudalis at 30 min before the experiment. In Nim-collated group, Nim (0.03 mg x kg(-1)) was injected into tail vein at the same time, while the mice in Sham-operated group and cerebral ischemia group were injected the same volume normal saline. The acute cerebral ischemia model was established by ligating bilateral common carotid arteries for 30 min in mice, then the mice were killed and the content of adenosine triphosphate (ATP), adenosine diphosphate (ADP), adenosine monophosphate (AMP), phosphocreatine (PCr) were observed, and the cerebral energy charge (EC) was computed. At the same time, activity of Na(+) -K(+) -ATPase and Ca2(+) -ATPase, content of water in brain tissue were measured.

RESULTCompared with cerebral ischemia group, EC and content of ATP, ADP, PCr in SalB-treated group heightened evidently (P < 0.01). Moreover, activity of Na(+)-K+ ATPase and Ca2+ ATPase in SalB-treated group had a remarkable increase (P < 0.01). But the content of water in brain tissue decreased markedly (P < 0.05).

CONCLUSIONThe mechanism that SalB can relieve content of water in brain tissue of cerebral ischemia in mice, may be associated with improving the content of high-energy phosphoric acid compounds and enhancing the activity of ATPase.

Adenosine Diphosphate ; metabolism ; Adenosine Monophosphate ; metabolism ; Adenosine Triphosphatases ; metabolism ; Adenosine Triphosphate ; metabolism ; Animals ; Benzofurans ; isolation & purification ; pharmacology ; Brain ; drug effects ; metabolism ; pathology ; Brain Ischemia ; physiopathology ; Calcium-Transporting ATPases ; metabolism ; Energy Metabolism ; drug effects ; Male ; Mice ; Phosphocreatine ; metabolism ; Plants, Medicinal ; chemistry ; Random Allocation ; Salvia miltiorrhiza ; chemistry ; Sodium-Potassium-Exchanging ATPase ; metabolism ; Water ; metabolism

This study aimed to observe the general state and changes in pathophysiological indexes of multiple cerebral infarction rat model with Qi-deficienty and Blood-stasis syndrome. Rats were randomly divided into 4 groups(with 30 in each group): the normal group, the sham group, the model group and the Yiqi Huoxue recipe group. Rats in the model group and Yiqi Huoxue group were provided with interruptable sleep deprivation for 7 days before the multiple cerebral infarction operation, and followed by another 4 weeks of sleep deprivation; rats in the Yiqi Huoxue group were intragastrically administrated with drug at a dose of 26 g·kg⁻¹, once a day for 4 weeks. The general state was observed, and the pathophysiological indexes were measured at 48 h, 2 weeks and 4 weeks after administration. The results showed that rats in the normal group and the sham group represented a good general state and behaviors, with a normal morphological structure of brain tissues; rats in the model group featured yellow fur, depression, accidie, loose stools and movement disorder, with obvious brain histomorphological damage, which became aggravated with the increase of modeling time; rats in the Yiqi Huoxue group showed release in the general state and above indexes. Compared with the sham group at three time points, rats in the model group showed decrease in body weight, exhaustive swimming time and RGB value of tongue surface image, and increase in whole blood viscosity of the shear rate under 5, 60 and 150 S⁻¹, reduction in cerebral cortex Na⁺-K⁺-ATPase, Ca²⁺-ATPase activity and contents of 5-HT, rise in TXB2 levels and decline in 6-keto-PGF1a in serum(<0.05, <0.01). Compared with the model group, rats in the Yiqi Huoxue group showed alleviations in the above indexes at 2 w and 4 w(<0.05, <0.01). The results showed that the characterization and pathophysiological indexes in the multiple cerebral infarction rat model with Qi-deficiency and blood-stasis syndrome were deteriorated; Yiqi Huoxue recipe could significantly alliviate the abnormal conditions, which suggested of the model was stable and reliable and the pathophysiologic evolutionary mechanism might be related to energy metabolism dysfunction, vasoactive substance abnormality and changes in neurotransmitters.
Animals ; Calcium-Transporting ATPases ; metabolism ; Cerebral Infarction ; physiopathology ; Drugs, Chinese Herbal ; pharmacology ; Energy Metabolism ; Medicine, Chinese Traditional ; Qi ; Rats ; Sodium-Potassium-Exchanging ATPase ; metabolism

The aim of this research is to investigate the effects of paeoniflorin and menthol on the physiological function of Calu-3 cell membrane during the transport of puerarin. Calu-3 cell was used as the cell model to simulate nasal mucosa tissues, and the cell membrane fluidity, Na⁺-K⁺-ATPase activity and Ca²⁺-ATPase activity were detected by fluorescence recovery after photobleaching(FRAP) and ultramicro enzyme activity testing, in order to explore the mechanism of compatible drugs on promoting puerarin transport. The results showed that when puerarin associated with low, middle and high concentration of menthol or both paeoniflorin and menthol, the fluorescence recovery rate was increased significantly, while Na⁺-K⁺-ATPase activity had no significant change and Ca²⁺-ATPase activity was enhanced significantly as compared with puerarin alone. Therefore, it was concluded that menthol had the abilit of promoting the transport and the mechanism might be related to increasing membrane fluidity and activating Ca²⁺-ATPase.
Calcium-Transporting ATPases ; metabolism ; Cell Line, Tumor ; Cell Membrane ; Glucosides ; chemistry ; Humans ; Isoflavones ; metabolism ; Membrane Fluidity ; Menthol ; chemistry ; Monoterpenes ; chemistry ; Sodium-Potassium-Exchanging ATPase ; metabolism

Adult ; Calcium-Transporting ATPases ; metabolism ; Erythrocyte Membrane ; metabolism ; Female ; Humans ; Hydrocarbons ; adverse effects ; Lipid Peroxidation ; Male ; Middle Aged ; Occupational Exposure ; Sodium-Potassium-Exchanging ATPase ; metabolism ; Young Adult

OBJECTIVETo study the effect of cerebral mild hypothermia on cerebral mitochondrial ATPase activities in neonatal rats with hypoxic-ischemic brain damage (HIBD).

METHODSEighty-four seven-day-old Wistar rats were randomly assigned into four groups: sham-operated normothermic, sham-operated mild hypothermic, HIBD normothermic and HIBD mild hypothemic. HIBD was induced by left common carotid artery ligation, followed by 8% hypoxia exposure. At each time interval of 2, 6, and 12 hrs post-hypoxia-ischemia (HI), 7 rats were sacrificed and the brain tissues were sampled for detecting the activities of mitochondrial Na+K+ATPase and Ca2+ATPase.

RESULTSThe activities of mitochondrial Ca2+ATPase decreased significantly in the two HIBD groups compared with those of the two sham-operated groups at 2, 6, and 12 hrs post-HI. The HIBD mild hypothemic group had higher mitochondrial Ca2+ATPase activities compared with the HIBD normothermic group at 2, 6, and 12 hrs post-HI (5.25 +/- 0.61 micromol/mgPr.h vs 3.17 +/- 0.81 micromol/mgPr.h 4.59 +/- 0.81 micromol/mgPr.h vs 2.26 +/- 0.53 micromol/mgPr.h4.61 +/- 0.62 micromol/mgPr.h vs 1.31 +/- 0.78 micromol/mgPr.H, respectively) (P < 0.01). The activities of mitochondrial Na+K+ATPase decreased significantly in the two HIBD groups compared with those of the two sham-operated groups at 6 and 12 hrs post-HI. A significant difference was observed in the mitochondrial Na+K+ATPase activities between the HIBD mild hypothemic and HIBD normothermic groups at 6 and 12 hrs post-HI (5.25 +/- 0.66 micromol/mg Pr.h vs 3.76 +/- 0.78 micromol/mgPr.h, 4.74 +/- 0.80 micromol/mgPr.h vs 3.12 +/- 0.53 micromol/mgPr.h; P < 0.01).

CONCLUSIONSMild hypothermia following HIBD inhibits the decline in cerebral mitochondrial Ca2+ and Na+K+ ATPase activities in neonatal rats, thus providing protective effects against HIBD.

Animals ; Animals, Newborn ; Brain ; enzymology ; Calcium-Transporting ATPases ; metabolism ; Female ; Hypothermia, Induced ; Hypoxia-Ischemia, Brain ; enzymology ; therapy ; Male ; Mitochondria ; enzymology ; Rats ; Rats, Wistar ; Sodium-Potassium-Exchanging ATPase ; metabolism

The purpose of the present study was to investigate whether interleukin-2 (IL-2) changes the activity of sarcoplasmic reticulum (SR) Ca(2+) ATPase, sarcolemmal Ca(2+)ATPase and Na(+)/K(+) ATPase by measuring the Pi liberated from ATP hydrolysis with colorimetrical methods. It was shown that the activity of Ca(2+)ATPase in SR from IL-2-perfused (10, 40, 200, 800 U/ml) rat heart increased dose-dependently. After incubation of the SR with ATP (0.1 approximately 4 mmol/L), the activity of SR Ca(2+)ATPase increased dose-dependently in the control group. In the SR from 200 U/ml IL-2-perfused hearts, the activity of Ca(2+)ATPase was much higher than that in the control group. On the other hand, incubation of the SR with Ca(2+) (1 approximately 40 micromol/L) increased the activity of SR Ca(2+) ATPase in the control group. The activity of SR Ca(2+)ATPase of IL-2-perfused hearts was inhibited as the function to Ca(2+). Pretreatment with specific kappa-opioid receptor antagonist nor-BNI (10 nmol/L) for 5 min attenuated the effect of IL-2 (200 U/ml) on the activity of SR Ca(2+) ATPase. After pretreatment with pertussis toxin (PTX, 5 mg/L) or U73122 (5 micromol/L), IL-2 failed to increase SR Ca(2+)ATPase activity. The activity of SR Ca(2+)ATPase was not changed by incubation of SR isolated from normal hearts with IL-2. Perfusion of rat heart with IL-2 did not affect the activity of sarcolemmal Ca(2+)ATPase and Na(+)/K(+)ATPase. It is concluded that perfusion of rat heart with IL-2 increases the activity of SR Ca(2+)ATPase dose-dependently, which is mainly mediated by cardiac kappa-opioid receptor pathway including a PTX sensitive Gi-protein and phospholipase C. IL-2 increases the activity of SR Ca(2+)ATPase as the function to ATP, but inhibits the activity of SR Ca(2+)ATPase as the function to Ca(2+). IL-2 has no effect on the activity of sarcolemmal Ca(2+)ATPase and Na(+)/K(+)ATPase.
Animals ; Interleukin-2 ; pharmacology ; Male ; Myocardium ; enzymology ; Rats ; Rats, Sprague-Dawley ; Sarcolemma ; enzymology ; Sarcoplasmic Reticulum ; enzymology ; Sarcoplasmic Reticulum Calcium-Transporting ATPases ; metabolism ; Sodium-Potassium-Exchanging ATPase ; metabolism

Animals ; Brain ; drug effects ; metabolism ; Calcium-Transporting ATPases ; metabolism ; Female ; Mice ; Mice, Inbred Strains ; Polychlorinated Dibenzodioxins ; toxicity ; Sodium-Potassium-Exchanging ATPase ; metabolism

Extracellular ATP (exATP) has been known to be a critical ligand regulating skeletal muscle differentiation and contractibility. ExATP synthesis was greatly increased with the high level of adenylate kinase 1 (AK1) and ATP synthase beta during C2C12 myogenesis. The exATP synthesis was abolished by the knock-down of AK1 but not by that of ATP synthase beta in C2C12 myotubes, suggesting that AK1 is required for exATP synthesis in myotubes. However, membrane-bound AK1beta was not involved in exATP synthesis because its expression level was decreased during myogenesis in spite of its localization in the lipid rafts that contain various kinds of receptors and mediate cell signal transduction, cell migration, and differentiation. Interestingly, cytoplasmic AK1 was secreted from C2C12 myotubes but not from C2C12 myoblasts. Taken together all these data, we can conclude that AK1 secretion is required for the exATP generation in myotubes.
Adenosine Triphosphate/*biosynthesis ; Adenylate Kinase/*metabolism ; Animals ; Cell Line ; Extracellular Space/metabolism ; Isoenzymes/*metabolism ; Mice ; Muscles/cytology/*metabolism

OBJECTIVETo investigate the mechanism of the negative inotropic effect of tumor necrosis factor-alpha (TNF-alpha) in cardiomyocytes.

METHODSThe spectrofluorometric method was used to verify the calcium handling of the single myocyte. The activities of Ca(2+)-ATPase of sarcoplasmic reticulum (SR) and the activities of Ca(2+)-ATPase and Na(+)/K(+)-ATPase of plasma membrane were measured with colorimetric methods.

RESULTSTNF-alpha at 20 U/ml and 200 U/ml depressed the contractility of ventricular papillary muscle to 91% and 76% of control (P<0.01) respectively, but had no effect on the amplitude of electrically induced calcium transient in single myocyte. TNF-alpha inhibited the responsiveness of SR Ca(2+)ATPase activity to ATP (0.1 - 4 mmol/L) and Ca(2+) (1 - 40 micromol/L). TNF-alpha did not alter the activities of Ca(2+)-ATPase and Na(+)/K(+)-ATPase of plasma membrane compared with control group.

CONCLUSIONTNF-alpha decreases the myocardial contractility, at least partly, by inhibiting the activity of SR Ca(2+)- ATPase.

Animals ; Calcium ; metabolism ; Calcium-Transporting ATPases ; metabolism ; Depression, Chemical ; In Vitro Techniques ; Male ; Myocardial Contraction ; drug effects ; Myocardium ; metabolism ; Rats ; Rats, Sprague-Dawley ; Sodium-Potassium-Exchanging ATPase ; metabolism ; Tumor Necrosis Factor-alpha ; pharmacology