Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0009443 (cold)
 92,137 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The iodides of three lipid-soluble cations (dibenzyldimethylammonium; tribenzylmethylammonium, TBMA+; ethyldimethylbenzylammonium) were synthesized by the reaction of 14C-labeled methyl or 14C-labeled ethyl iodide with the appropriate secondary of tertiary amine and used in an attempt to measure the transmembrane electrical potential difference in Neocosmospora. Only mycelium containing high levels of Na+ accumulated measureable amounts of these cations and only above pH 6. Uptake was reduced in the presence of exogenous K+, Na+, Mg2+, or tris(hydroxymethyl)aminomethane. The velocity of TBMA+ uptake was proportional to its concentration between 46 and 427 muM. Neither the rate nor the extent of TBMB+ uptake was greatly affected by the presence of a fivefold excess of either dibenzyldimethylammonium or ethyldimethylbenzylammonium, even though these cations were themselves accumulated. The uncoupler m-chlorophenylhydrazone induced loss of previously accumulated TBMA+ from the mycelium. Anaerobiosis and cold (5 degrees C) temperature both inhibited TBMA+ uptake but did not induce the loss of previously accumulated TBMA+. The uptake of lipophilic cations by Na+-rich mycelium indicated a minimum transmembrane electrical potential of -60 to -70 mV (inside negative). Net uptake of these cations appeared to be strongly influenced by the availability of endogenous exchangeable cations and by the presence of other exogenous cations, as well as by the membrane potential. Despite these limitations, transport of C1- by Na+-rich mycelium appeared to take place against the electrochemical gradient for C1-.
 ...
PMID:Evidence for a negative membrane potential and for movement of C1- against its electrochemical gradient in the ascomycete Neocosmospora vasinfecta. 1 Dec 6

Mouse L cells can be made permeable to exogenous nucleotides by a cold shock in 0.01 M Tris . HCl pH 7.8, 0.25 M sucrose, 1 mM EDTA, 30 mM 2-mercaptoethanol and 4 mM MgCl2. DNA synthesis in permeabilized L cells requires ATP whereas DNA synthesis in permeabilized L cells that are infected with Vaccinia virus is ATP-independent. Permeabilized L cells that are infected with ultraviolet-irradiated virus show a marked suppression of DNA synthesis which is not corrected by an excess of deoxynucleoside triphosphates and ATP. The ATP-dependent and ATP-independent processes of DNA synthesis are inhibited to the same extent by Mal-Net, pHMB, ara CTP and phosphonoacetate. Concentrations of daunorubicin and cytembena, which cause marked inhibition of the ATP-dependent enzymes, only cause partial inhibition of the ATP-independent enzymes.
 ...
PMID:ATP-independent DNA synthesis in vaccinia-infected L cells. 71 13

1. The intracellular Cl- concentration, [Cl-]1, of rat renal outer medullary slices has been studied in iso-osmolal media containing 42, 93, 144, 189 or 225 mM chloride, [Cl-]0. Equilibrium values for [Cl-]1 were attained within 25-50 min from the start of incubation such that [Cl-]1/[Cl-]0 = 0-46. This ratio was independent of [Cl-]0 within the range studied. Intracellular Na+ was unaffected, and only minor variations of cell volume were observed (calculated from slice weight changes and [14C]carboxyl inulin spaces. 2. When [Cl-]0 = 189 mM, [Cl-]1 remained constant at 87 mM for up to 50 min, indicating that these figures may represnet the interstitial [Cl-] and mean intracellular [Cl-] respectively in outer medulla. 3. Omission of bicarbonate from medium containing 189 mM-Cl- caused an increase in [Cl-]1/[Cl-]0 to 0-58, which was not significantly affected by anoxia or by the presence of arsenite (5 X 10(-3) M) or 2,4-dinitrophenol (10(-3) M). Significant further increases were observed in the presence of iodoacetic acid (5 X 10(-3) M) (0-70), acetazolamide (10(-3) M or 5 M 10(-3) M) (0-71) and iodacetic acid plus 2,4-dinitrophenol (0-85). The addition of the diuretic agents ouabain, ethacrynic acid-cysteine and frusemide (all 10(-3) M) to 189 mM-Cl- media containing bicarbonate reduced [Cl-]1/[Cl-]0 to 0-36, 0-37 and 0-42 respectively. 4. The mean 36Cl- space of outer medulla after 50 min incubation in 189 mM Cl- medium was 49-7 +/- 2-1 micronl./100 mg wet wt. The volume of distribution was not significantly affected by ouabain, ethacrynic acid-cysteine or frusemide (10(-3) mM). 5. Net efflux of 36Cl- from slices loaded with isotope into 'cold' 189 mM Cl medium showed three components with rate constants of 69 X 10(-3), 18 X 10(-3) and 9-9 X 10(-5) sec-1 respectively. Efflux was not affected by ouabain, ethacrynic acid-cysteine or frusemide (10(-3) mM). 6. The main conclusions drawn from this study are: (i) the interstitial fluid Cl- concentration of normally hydrated rat outer medulla is approx. 189 mM; (ii) the [Cl-]1/[Cl-]0 ratio 0-46 may represent a chiefly passive distribution maintained by the opposing gradient of a second anion, probably bicarbonate; (iii) the energy required to maintain unequal distribution of Cl- in the absence of external bicarbonate is derived chiefly from glycolysis, with a small aerobic component; (iv) there may be two intracellular chloride pools whose net rates of Cl- exchange differ by a factor of approx. 180.
 ...
PMID:Factors affecting the distribution of chloride ions in rat renal outer medulla. 85 97

(1) Net Na+ loss from rabbit ileum, stripped of its serosal muscle layers, into ice cold choline chloride is consistent with loss from two separate pools (rate constants 0.102 and 0.011 min-1). Since cell K+ is lost with a single rate constant, 0.0062 min-1) and inulin, a good extracellular marker, is lost with a single rate constant 0.082 min-1, it is inferred that the fast rate constant of Na loss characterizes loss from an extracellular pool and the slow constant, loss from an intracellular pool. (2) The [Na+] in the inulin space (extracellular) was calculated to be 180 +/- 13 (S.D.) mequiv. and the [Na+] in the intracellular space 30.4 +/- 4.1 (S.D.) medquiv., this provides evidence that the paracellular spaces are, at least 80 mosmol hypertonic to the external Ringer. (3) There is a saturable galactose-dependent increase in both the intracellular and extracellular [Na+]. Extracellular [Na+] is increased to 236 +/- 22 (S.D.) mequiv. Whilst intracellular [Na+] is increased to 42.6 +/- 8.8 (S.D.) mequiv. when Ringer [galactose] is 10 mM. Galactose-dependent increases in total tissue [Na+] can thus be attributed mainly to the increase in extracellular [Na+]. (4) Extracellular hypertonicity, both in the presence and absence of galactose, is dependent upon the [Na+] of the bathing Ringer. 0.1 mM ouabain abolishes the extracellular hypertonicity. This observed extracellular hypertonicity in normally functioning tissue may provide the driving force for transcellular convective flow of salt, water and sugars.
 ...
PMID:Factors affecting the compartmentalization of sodium ion within rabbit ileum in vitro. 97 41

1. Young steers were fed either 3-4 or 20 h before exposure to a thermoneutral or a moderately cold environment. Measurements were made of total oxygen consumption (total V 0-2), respiratory quotient (rq), blood packed cell volume (PCV), and hind-leg blood flow (leg Q) and oxygen uptake (leg VO-2). The arteriovenous differences in whole blood glucose, lactate and pyruvate, and individual amino acid and urea concentrations across the leg were also measured. Net exchange and fractional uptake of these metabolites by the leg were calculated from these results. 2. Cold exposure doubled total VO-2, significantly decreased RQ and significantly increased PCV. Leg Q and leg VO-2 increased 3- to 5-fold and 4- to 13-fold respectively in both feeding groups. Arterial blood glucose increased slightly but significantly in both 20 h- and 3 h-fed steers. There was a substantial increase in mean net leg uptake of glucose in both feeding groups. This was much greater in the 20 h-fed group because of the significant increase in fractional uptake occurring only in this group. Cold did not significantly affect arterial blood lactate or pyruvate levels, but the net leg output of lactate found in both feeding groups in thermoneutrality was increased in the 20 h-fed steers, and reversed to a net uptake in the 3 h-fed animals. Cold caused a small but significant decrease in the total plasma amino acid level in the 20 h-fed but not in the 3 h-fed group; individual amino acid levels or leg uptakes were not affected. 3. Feeding before the experiment caused a significant increase in RQ. Leg Q, leg uptake of glucose and leg output of lactate increased after feeding in the thermoneutral environment only. Arterial pyruvate increased significantly, but net leg output was not significantly affected by feeding. Arterial plasma concentration of several individual, but not of total amino acids, increased significantly in both environments, and the net output of many individual amino acids in the 20 h-fed steers was decreased or reversed to a net uptake in the 3 h-fed group in thermoneutrality only. 4. The results suggest that blood glucose could be a significant fuel for oxidation in shivering skeletal muscle in young steers, and that output of amino acids from skeletal muscle could not contribute significantly to this increased glucose supply by hepatic gluconeogenesis.
 ...
PMID:Acute cold exposure and the metabolism of blood glucose, lactate and pyruvate, and plasma amino acids in the hind leg of the fed and fasted young ox. 111 60

Free-flow micropuncture experiments were done in rats of three strains infused with small amounts of urate [plasma urate (P urate) = 95 +/- 8 muM]. Urate concentrations in tubular fluid were measured by an accurate chemical fluorometric ultramicromethod. In fluid from surface glomeruli, the glomerular fluid-to-plasma urate ratio [GF/P) urate] was 0.99 +/- 0.03 (n=11), i.e., lower than expected for total ultrafiltrability of plasma urate. Along proximal convolutions, net reabsorption of 55% of filtered urate was demonstrated. Small amounts of urate may have been reabsorbed between late proximal and early distal sites. Net transepithelial movements of urate did not occur in distal tubules or collecting ducts. In microperfusion experiments on proximal tubules, both a reabsorptive flow of urate (loss of perfused [2-14C]urate) and a secretory flow (entrance of cold urate into perfusate) of the same order of magnitude were demonstrated. Neither flow was influenced by simultaneous water movements. Microperfusion of Henle's loops indicated a significant but very small net reabsorption.
 ...
PMID:Renal excretion of uric acid in the rat: a micropuncture and microperfusion study. 126 82

Methylmercury (MeHg) efflux from rat astrocyte cultures was studied to complement our previous studies on uptake of MeHg in these cells. Exchange with extracellular MeHg was not obligatory for the efflux of [203Hg]MeHg into the extracellular media, because efflux occurred into MeHg-free extracellular media, but stimulation of [203Hg]MeHg net efflux was shown when astrocytes were equilibrated in the presence of 'cold' MeHg and graded concentrations of L-cysteine. Net efflux of MeHg was most rapid for the first 5 min, and approximately 20% of preloaded [203Hg]MeHg was lost from the astrocytes by 60 min. Uptake of [203Hg]MeHgCl was maximal by 30 min and did not increase when the loading period was extended up to 4 h. However, the total amount of intracellular 203Hg that was available for net efflux gradually decreased as the duration of the preloading period increased. MeHg net efflux from astrocytes was unchanged when [203Hg]MeHgCl preloaded astrocytes were equilibrated in hypotonic buffer, suggesting that unlike ions and amino acids swollen astrocytes remain impervious to MeHg efflux. Thus, the main MeHg efflux transport system is apparently specific for the MeHg-L-cysteine conjugate and represents transport by the same neutral amino acid System L that facilitates its uptake.
 ...
PMID:Interactions of methylmercury with rat primary astrocyte cultures: methylmercury efflux. 193 94

Reduced thermogenesis in brown adipose tissue (BAT) may contribute to increased energetic efficiency and obesity in rats with ventromedial hypothalamic (VMH) lesions. Thermogenic activity of BAT is a function of the environmental temperature. If a relationship exists, it follows that the increased energetic efficiency of VMH-lesioned rats likewise should be governed by temperature. We have therefore investigated the energy balance of normal and VMH-lesioned rats housed at 30 degrees C and 10 degrees C. Experiments at differing feeding levels allowed calculation of maintenance energy requirements and the net energetic efficiencies of each group. VMH-lesioned rats at thermoneutrality (30 degrees C) accumulated more body fat at all feeding levels than did normal rats. Maintenance energy requirement was reduced, but the net energetic efficiency did not differ significantly from normal. The reduced maintenance energy requirement of lesioned rats persisted at 10 degrees C. Net energetic efficiency decreased in normal rats acclimated to cold but increased in the lesioned group. The difference was significant (P less than 0.05). The cold-induced increase in interscapular brown adipose tissue (IBAT) oxidative capacity of VMH-lesioned rats was only half that of normal rats. Differences in BAT thermogenesis may be the basis for the differing temperature effects on net energetic efficiency.
 ...
PMID:Opposite effect of cold on energetic efficiency in normal and obese Wistar rats with hypothalamic lesions. 200 9

Net fluid absorption (Jv), cell volume, and cell membrane area have been studied in isolated, perfused snake (Thamnophis spp.) proximal tubules. With Na+ in both perfusate and bathing medium, Jv averages approximately 0.9 nl.min-1.mm-1. When choline replaces Na+ in perfusate, Jv nearly ceases. When choline also replaces Na+ in bathing medium, so that both solutions are identical, Jv returns to the control rate. The results are the same when tetramethylammonium replaces Na+, when sucrose replaces Na+ and the equivalent amount of Cl-, and when methyl sulfate replaces Cl- alone. However, when Li+ replaces Na+ in perfusate alone or in both perfusate and bathing medium, Jv is unchanged. Jv at control rates is isosmotic and can be partially inhibited by cold and cyanide. When choline replaces Na+ in perfusate and bathing medium, cell volume doubles, and intercellular space volume nearly quintuples. The areas of the lateral and apical cell membranes also approximately double, so that the surface area-to-volume ratio remains constant. These morphological changes in the absence of Na+ occur concomitantly with maintenance of Jv, suggesting that they may play a permissive role in such maintenance.
 ...
PMID:Membrane dynamics in relation to fluid absorption in reptilian proximal renal tubules. 268 69

1. Thermo-electric observations of temperature distribution in the ;core' area of monkeys and baboons are reported.2. Temperature gradients were shown to exist in the inferior vena cava, temperatures rising by a mean value of 0.2 degrees C at the entry of the renal veins and again by a further 0.2 degrees C at the level of the hepatic veins.3. Temperatures in the right atrium were on average 0.1 degrees C lower than in the inferior vena cava due to the return of relatively cooler blood from the superior vena cava.4. Net heat exchanges in the thorax were small. Right atrial and aortic blood temperatures were not significantly different and it was concluded that heat losses in the thorax were balanced by heat production in lungs and heart.5. The mean liver temperature was 0.1 degrees C higher than that of the aortic blood irrespective of the environment.6. The mean temperature recorded from the lumen of the jejunum was 0.2 degrees C warmer than the aorta in the ;warm' environment and 0.4 degrees C hotter than the aorta in the ;cool' environment. In both environments intrajejunal temperature was higher than the liver but the differential was increased by exposure to a ;cool' environment.7. Evidence is adduced to suggest that the gastro-intestinal tract in the body at rest is a major heat producer contributing about double the amount of heat generated by the liver.8. It is suggested that blood flow redistribution in the splanchnic area on exposure of the body to cold is the main cause of the change in aortic-jejunal and jejunal-liver differentials. Metabolic factors have, however, not been excluded.
 ...
PMID:Observations on temperature distribution in the cardiovascular system, thorax and abdomen of monkeys in relation to environment. 496 Apr 30


1 2 3 4 5 Next >>