Species differences in epinephrine concentration and norepinephrine N-methyltransferase activity in hypothalamus and brain stem

1. The concentration of epinephrine, norepinephrine and dopamine, and the activity of norepinephrine N-methyltransferase, the epinephrine-forming enzyme, were determined in hypothalamus and brain stem in several species. 2. Epinephrine concentration in hypothalamus, a nerve terminal region, varied in the order frog greater than turtle greater than chicken greater than cat greater than dog greater than pigeon greater than rat greater than ferret greater than hamster greater than mouse, with concentrations being undetectable in rabbits, horses and guinea pigs. 3. Epinephrine concentration was lower than norepinephrine concentration in all species except the frog. 4. NMT activity was detected in all species except guinea pigs. 5. Epinephrine concentration was lower in brain stem, a cell body region, than in hypothalamus in all species. Only in the frog brain stem was there more epinephrine than norepinephrine. 6. No epinephrine or NMT activity was detected in either brain region in guinea-pigs.     

The bindings of 3H-prazosin and 3H-yohimbine to alpha adrenoceptors in the guinea-pig stomach

Alpha adrenoceptor subtypes have been investigated by radioligand binding study in guinea-pig stomach using 3H-prazosin and 3H-yohimbine. The specific 3H-prazosin binding to guinea-pig stomach was saturable and of high affinity (KD = 1.4 nM) with a Bmax of 33 fmol/mg protein. Specific 3H-yohimbine binding to the tissue was also saturable and of high affinity (KD = 25.5 nM) with a Bmax of 150 fmol/mg protein. Adrenergic drugs competed for 3H-prazosin binding in order of prazosin greater than phentolamine greater than methoxamine greater than norepinephrine greater than clonidine greater than epinephrine greater than yohimbine. These drugs competed for 3H-yohimbine binding in order of yohimbine greater than phentolamine greater than clonidine greater than epinephrine greater than norepinephrine greater than prazosin greater than greater than prazosin greater than methoxamine. We also examined whether dopamine receptors exist in guinea-pig stomach, using radioligand binding study. Specific binding of 3H-spiperone, 3H-apomorphine, 3H-dopamine and 3H-domperidone was not detectable in the stomach. Dopaminergic drugs such as dopamine, haloperidol, domperidone and sulpiride competed for 3H-prazosin binding in order of haloperidol greater than domperidone greater than dopamine greater than sulpiride. Metoclopramide, sulpiride and dopamine competed for 3H-yohimbine binding in order of metoclopramide greater than sulpiride greater than dopamine. These results suggest that guinea-pig stomach has alpha 1 and alpha 2 adrenoceptors and has no specific dopamine receptors. It is also suggested that some dopamine receptor antagonists such as domperidone, haloperidol, sulpiride and metoclopramide have antagonistic actions on alpha adrenoceptors.     

Effect of ion adsorption on the electrokinetic properties of erythrocytes

The microelectrophoresis technique was used to determine the dependence of human erythrocyte surface potential on the concentration of various cations and anions. The interpretation of the results is based on the Gouy--Chapman--Stern theory. Values of pK, characterizing the binding of ions to the external surface of erythrocytes, as well as numbers of binding sites per unit area were determined. The affinities of ions for the red cell membrane were shown to decrease in the sequence: H+ greater than Ca2+ greater than Sr2+ greater than Mg2+ greater than Ba2+ greater than Li+ greater than Na+ congruent to congruent to K+ congruent to NH4+ and trinitrophenol greater than IO4- greater than CIO4- greater than salicylate congruent to I- greater than greater than SCN- greater than H2PO4- greater than Br- greater than Cl- greater than HPO4(2-). Changes in the ionic strength of the medium resulted in changes in numbers of exposed ion-binding sites. This phenomenon is interpreted in terms of ionic strength-dependent structural transformations of the cell surface coat.     

Sugar best single chorda tympani nerve fiber responses to various sugar stimuli in rat and hamster

1. Sugar best single chorda tympani nerve fiber of rat and hamster were tested with six sugars. 2. Fibers were selected for this experiment, only if they responded to 1.0 M sucrose or 1.0 M maltose and they responded poorly to 0.1 M NaCl. 3. In rat, some single fibers gave larger responses to maltose than to sucrose, while in hamster nearly all nerve fibers responded best to sucrose. 4. The order of effectiveness of sugars was maltose greater than fructose greater than or equal to lactose greater than sucrose greater than glucose greater than galactose in rat and sucrose greater than fructose greater than or equal to glucose greater than or equal to galactose greater than maltose greater than lactose in hamster.     

Effect of ethanol on serum electrolytes and osmolality

Rats and rabbits were injected ethanol 2 g/kg intraperitoneally. One hour after injection blood was analyzed for serum electrolytes and osmolality. Administration of ethanol caused decrease in serum sodium (p less than 0.0005), potassium (p less than 0.0005), calcium (p less than 0.0005), chloride (p less than 0.005), magnesium (p less than 0.0005) in rabbits. Further studies of intraperitoneal administration of ethanol in rats showed decrease in concentration of sodium (p less than 0.025), potassium (p less than 0.025), calcium (p less than 0.01) chloride (p less than 0.005) magnesium (p less than 0.005), phosphorus (p less than 0.025) and glucose (p less than 0.005). Administration of ethanol caused an increase in serum osmolality in both rabbits and rats (p less than 0.005, p less than 0.05). It is concluded that ethanol ingestion is probably the commonest cause of the hyperosmolar state. Although the osmotic and sedative effects of ethanol are pharmacologically unrelated, the presence of ethanol should be considered in comatose patients in whom the measured plasma osmolality appreciably exceeds that predicted on the basis of plasma glucose, urea and electrolytes concentration.     

A novel imino-acid carrier in the enterocyte basolateral membrane

Basolateral membrane vesicles prepared from rat small intestinal epithelial cells were used to study the sodium-independent transport of L-proline. The uptake of L-proline was unaffected by the presence of sodium and showed saturation kinetics (Kt = 0.5 mM and Vmax = 23.3 pmol/mg protein per s). Competition experiments indicated that other amino acids had an affinity for the carrier system with L-leucine greater than L-alanine greater than sarcosine greater than glycine greater than L-lysine greater than OH-proline greater than taurine greater than beta-alanine greater than D-alanine greater than D-proline greater than L-serine greater than phenylalanine greater than valine greater than D-serine greater than phenylalanine greater than valine greater than D-serine greater than MeAIB greater than methionine greater than threonine. This pathway does not resemble those previously described either in the brush-border membrane of intestinal epithelial cells or the plasma membrane of other cell types. The lack of effect of methionine and threonine indicate that proline is not using the L-type system, while the very low affinity for MeAIB and the Na+ independence suggest that this is a novel system for imino acids. The relatively high capacity of this system and its low Kt, which is almost identical to the proline system in the brush-border membrane, strongly suggest that this is an important pathway in the final step for proline absorption by the small intestine.     

A comparative study of superoxide dismutase in various animal species

1. Superoxide dismutase activity has been determined in liver homogenates of five species. There were no significant differences in the activities of the enzyme in the rat, rainbow lizard, wall gecko and chicken. The activity was significantly lower in the fish. 2. The order of activity of the enzyme in the organs/tissues of the rat was liver greater than kidney greater than heart greater than skeletal muscle greater than brain greater than lung greater than spleen greater than spinal cord greater than retina greater than pancrease greater than lens greater than small intestine. 3. Inhibition studies with cyanide showed that the enzyme in the liver of the various animal species was inhibited by cyanide. 4. The developmental pattern for the enzyme showed no significant changes in the liver of the rat from birth and up to 7 weeks after. However, the activity increased at about 8 weeks and remained constant to adult life.     

The synthesis of glucose and ammonia by kidney tubules isolated from suckling and early-weaned lambs

Glucose and ammonia production were examined in kidney tubules isolated from suckling and early-weaned lambs, on days 10-30 after birth, with abrupt weaning occurring at day 14. There were no differences in the rates of glucose or ammonia production for a given substrate by tubules isolated from any of the lambs, regardless of age or stage of weaning. The preferred substrates for gluconeogenesis were glycerol = lactate greater than propionate = pyruvate = fructose = proline greater than alanine greater than glutamate greater than glutamine greater than aspartate greater than glycine greater than serine, and for ammoniagenesis were glutamine much greater than alanine greater than aspartate much greater than serine greater than glycine = glutamate = proline.     

Comparison of the fecal microflora in rural Japanese and urban Canadians

The fecal microflora of nine rural healthy Japanese and eight urban healthy Canadians was examined. The two populations ate typical Japanese and western diets, respectively. The numbers of eubacteria (P less than 0.01), bifidobacteria (P less than 0.05), bacilli (P less than 0.01), lactobacilli and veillonellae and the frequency of occurrence of bifidobacteria were higher in the Japanese than in the Canadians. Higher numbers of bacteroides and lecithinase-negative clostridia were found in the Canadians. Twenty-three genera and over 75 species or biovars were isolated from the feces of Japanese and 18 genera and over 66 species or biovars from the Canadians. The numbers of Bacteroides vulgatus (P less than 0.05), Clostridium coccides (P less than 0.001), and C. tertium (P less than 0.05) and the incidence of B. uniformis (P less than 0.01), C. innocuum (P less than 0.05), and Bacillus spp. (P less than 0.01) were significantly lower in the Japanese than in the Canadians. In contrast, the numbers of Eubacterium aerofaciens (P less than 0.001), and the incidence of Bifidobacterium adolescentis biovar b (P less than 0.01) and Bacillus subtilis (P less than 0.01) were significantly higher in the Japanese than in the Canadians. These findings suggest that significant reductions in anaerobic gram-positive bacilli and increased numbers of bacteroides and clostridia in the feces were induced by the intake of a western diet.     

The cation specificity of the potassium and gramicidin channels of muscle fiber membrane

Conductance ratios (Gi/Gk) and permeability ratios (Pi/Pk) for monovalent cations in frog muscle fibres have been defined under constant current conditions using a double sucrose gap method. Selectivity determined from potassium channel conductance is: K+ greater than Rb+ greater than Cs+ greater than greater than NH4+ greater than Na+ greater than Li+. In gramicidin channels both the permeability and conductance sequences are identical: NH4+ greater than Cs+ greater than Rb+ greater than K+ greater than Na+ greater than Li+. In isotonic K+-sulfate solution with one-sided addition of external [Tl+] (2.5 x 10(-3)-20 x 10(-3) M), differences in the conductance and permeability ratios for gramicidin channel were observed.     

Development of the testicular interstitium after neonatal hemicastration in the boar

Development of the prepubertal interstitium of the right testes was characterized every 14 days from 10 to 122 days of age in intact boars (I) and boars hemicastrated (HC) at 10 days of age from two herds (Trial 1 and Trial 2). Comparisons were made between the remaining testis of Group-HC boars and one testis in Group-I boars. The relative mass (mass of component/body mass) of interstitium was 151% greater (P less than 0.001) in Group-HC than Group-I boars by 52 days of age. The relative mass of interstitium was greater (P less than 0.01) in Trial-1 than Trial-2 boars within each treatment from 80 to 122 days of age. The relative mass of interstitial space was 76% greater (P less than 0.05) in Group-HC than in one testis of Group-I boars by 52 days of age and greater (P less than 0.05) in Trial-1 than Trial-2 boars within each treatment from 80 to 122 days of age. The relative mass of Leydig cells was 254% greater (P less than 0.0001) in Group-HC than Group-I boars by 52 days of age and remained greater (P less than 0.05) in Group-HC than Group-I boars from 52 to 122 days of age. By 52 days of age the relative mass of Leydig cell nuclei and cytoplasm was 235% and 265% greater (P less than 0.0001) in Group-HC than Group-I boars, respectively, and both remained greater (P less than 0.05) in Group-HC than in Group-I until 122 days of age.(ABSTRACT TRUNCATED AT 250 WORDS)     

Cation and anion sequences in dark-adapted Balanus photoreceptor.

Anion and cation permeabilities in dark-adapted Balanus photoreceptors were determined by comparing changes in the membrane potential in response to replacement of the dominant anion (Cl-) or cation (Na+) by test anions or cations in the superfusing solution. The anion permeability sequence obtained was PI greater than PSO4 greater than PBr greater than PCl greater than Pisethionate greater than Pmethanesulfonate. Gluconate, glucuronate, and glutamate generally appeared more permeable and propionate less permeable than Cl-. The alkali-metal cation permeability sequence obtained was PK greater than PRb greater than PCx greater than PNa approximately PLi. This corresponds to Eisenman's IV which is the same sequencethat has been obtained for other classes of nerve cells in the resting state. The values obtained for the permeability ratios of the alkali-metal cations are considered to be minimal. The membrane conductance measured by passing inward current pulses in the different test cations followed the sequence, GK greater than GRb greater than GCs greater than GNa greater than GLi. The conductance ratios obtained for a full substitution of the test cation agreed quite well with permeability ratios for all the alkali-metal cations except K+ which was generally higher.     

Fungitoxicity of 1,4-naphthoquinones to Candida albicans and Trichophyton mentagrophytes.

Twenty-one substituted 1,4-naphthoquinones and five 8-quinolinols and copper(II) chelates were tested for antifungal activity against Candida albicans and Trichophyton mentagrophytes. Compounds containing electron-releasing or weak electron-withdrawing groups in the 2 and 3 positions of the 1,4-naphthoquinone ring were the most active against C. albicans at pH 7.0 in the presence of beef serum in the following order: 2-CH3O = 2,3-(CH3O)2 greater than 2-CH3 greater than 2-CH3S greater than 2-NH2 greater than 2,6-(CH3)2. For T. mentagrophytes under the same conditions the inhibitory 1,4-naphthoquinones contained the substituents 2-CH3O greater than 2,3-(CH3O)2 greater than 2-CH2S greater than 2-CH3 greater than 2-CH3(NaHSO3) greater than 2-NH2 greater than 2-C2H5S, 3-CH3 greater than 2,6-(CH3)2 greater than 2,3-CL2 greater than 5,8-(OH)2.     

Distribution of adenosine deaminase in some rat tissues. Inhibition by ethanol and dimethyl sulfoxide

The level of adenosine deaminase in various rat tissues has been tested. The enzyme activity of cytosolic fractions decreased in the following order: lung greater than spleen greater than small intestine greater than stomach greater than kidney greater than heart greater than liver greater than skeletal muscle greater than forebrain greater than cerebellum. The enzyme had identical patterns from tissue to tissue with respect to Km, V, and Ki values for ethanol and for dimethyl sulfoxide, with respect to electrophoretic behaviour and to inhibition by antibodies anti-rat brain adenosine deaminase.     

Pharmacological characterisation of the dopamine-sensitive adenylate cyclase in cockroach brain: evidence for a distinct dopamine receptor

Dopamine increases cyclic AMP production in crude membrane preparations of cockroach brain with plateaus in cyclic AMP production occurring between 1-10 microM and at 10 mM. Maximal production of cyclic AMP is 2.25 fold greater than that of control values. Octopamine also increases cyclic AMP production with a Ka of 1.4 microM and maximal production 3.5 fold greater than that of control. 5-Hydroxytryptamine does not increase cyclic AMP production. The effects of octopamine and dopamine are fully additive. The vertebrate dopamine agonists ADTN and epinine stimulate the dopamine-sensitive adenylate cyclase (AC) with Ka values of 4.5 and 0.6 microM respectively and with maximal effectiveness 1.7 fold greater than that of control. The selective D2-dopamine agonist LY-171555 stimulates cyclic AMP production to a similar extent with a Ka of 50 microM. Other dopamine agonists (apomorphine, SKF-82526, SKF-38393) have no stimulatory effects. The octopamine-sensitive AC is inhibited by a variety of antagonists known to affect octopamine and dopamine receptors, with the following order of potency: mianserin greater than phentolamine greater than cyproheptadine greater than piflutixol greater than cis-flupentixol greater than SCH-23390 greater than (+)-butaclamol greater than SKF-83566 greater than SCH-23388 greater than sulpiride greater than spiperone greater than haloperidol. The dopamine-sensitive AC is inhibited by the same compounds with the following order of potency: piflutixol greater than cis-flupentixol greater than (+)-butaclamol greater than spiperone greater than or equal to SCH-23390 greater than cyproheptadine greater than SKF-83566 greater than SCH 23388 greater than mianserin greater than phentolamine greater than sulpiride greater than haloperidol. With the exception of mianserin, 3H-piflutixol is displaced from brain membranes by dopamine antagonists with an order of potency similar to that observed for the inhibition of dopamine-sensitive AC. The results indicate that the octopamine- and dopamine-sensitive AC in cockroach brain can be distinguished pharmacologically and the dopamine receptors coupled to AC have pharmacological characteristics distinct from vertebrate D1- and D2-dopamine receptors.     

Anion permeation in the proximal tubule of Necturus kidney: the shunt pathway.

The effect of foreign anions on transepithelial potential difference and transepithelial input conductance was studied in the isolated perfused Necturus kidney. Two microelectrodes (recording and current-injecting) were inserted into the lumen of single proximal tubules and the peritubular perfusate was shifted reversibly for 30-60 sec from a physiologic Ringer's solution to a test solution in which chloride was replaced isosmotically by a foreign anion. The permeability sequence, obtained by potential measurements, was: lactate less than glutamate less than gluconate less than pyruvate less than benzene sulfonate less than or equal to acetate less than or equal to F less than propionate less than BrO3 less than formate less than ClO3 less than Cl than ClO4 less than I less than or equal to Br less than NO3 less than SCN. Transepithelial conductance decreased when the tissue was perfused with anions less permeable than chloride but the conductance sequence was different from the permeability sequence. Such discrepancies were more pronounced during perfusion with hyperpolarizing anions; ClO4 and I- (both more permeable than chloride) produced an important decrease in transepithelial conductance, followed by incomplete reversibility when the perfusion was shifted again to chloride Ringer's. The results are best explained by the presence of weak positive fixed charges, governing anion permeation, at the shunt pathway of the proximal tubule. An analysis of the data allows tentative estimates of shape and size of the sites.     

Energetics of the hairpin to mismatched duplex transition of d(GCCGCAGC) on NaCl solution

We report Potential of Mean Force studies to describe the relative thermodynamic stabilities of d(GCCGCAGC) in a mismatched duplex and a hairpin monomer conformation in NaCl solution. The PMF calculations are combined with previous molecular mechanics and normal mode analysis in order to estimate the role of different components of the free energy in determining the relative stability of the duplex and hairpin structures. The high entropy associated with the loop region and the lack of minor groove phosphate-phosphate interactions in the hairpin compete against the gain in enthalpic contribution to the free energy due to base pairing in the mismatched duplex. The combined free energy calculations show that the hairpin is the most stable conformation at low salt and that a hairpin to duplex transition takes place at approximately 0.47 M NaCl. In addition, we studied the hairpin to partially stacked single helical conformation equilibrium at low salt. We found a small variation in transition temperature in salt concentration, delta Tm/delta log10(cs) approximately 2-3 degrees K/decade, in contrast to the duplex to hairpin or duplex to partially stacked single helix transition where the transition temperature exhibited marked dependence on salt concentration. This is in qualitative agreement with experimental data. Based on the Potential of Mean Force free energy calculation, the order of relative stability of the three-conformations studied varies with salt concentration. We observed the following orders of stability: stacked single helix greater than hairpin greater than duplex for cs less than 0.77 M NaCl; single helix greater than duplex greater than hairpin for 0.77 less than Cs less than 2.1 M; and duplex greater than hairpin greater than single strand for cs greater than 2.1 M. From the calculated PMF free energy curves in the NaCl concentration range, 0.012 less than cs less than 5.0 M, we can assign upper and lower bounds for the non-ionic differences in free energy between the duplex, hairpin, and stacked single helical states (at standard conditions: cs = 1.0 M, T = 25 degrees C, and 1 M oligomer concentration). We found that for delta G duplex single helix = G duplex - 2 x G single helix less than -7.38 Kcal/mol, the single helix is the least stable state. For the duplex-to-hairpin free energy difference in the range, -1.87 less than delta G duplex-hairpin less than 0.03 Kcal/mol, there will always be a salt-induced hairpin-to-duplex transition for 0.01 less than cs less than 1.6 M NaCl. If delta G duplex-hairpin less than -1.87, the duplex is always more stable than the hairpin; and for delta G duplex-hairpin greater than Kcal/mol, the hairpin state is always more stable than the duplex, for all salt concentrations.     

Detection and distribution of scorpion (Heterometrus bengalensis) venom in rabbit tissues by enzyme-linked immunosorbent assay (ELISA).

ELISA was carried out to detect distribution of scorpion venom in experimental animal tissues. The venom content of different tissues was in the order, liver greater than kidney greater than spleen greater than lung greater than heart greater than diaphragm greater than brain. Tissue distribution of venom antigen in the envenomental subject by ELISA will provide a better approach for serotherapy.     

Vitamin A toxicity and hypercalcaemia in chronic renal failure.

Serum vitamin A concentrations were measured in 38 patients undergoing haemodialysis, 24 of whom were taking multivitamin preparations containing vitamin A. Vitamin A concentrations were significantly higher in patients undergoing haemodialysis than in 28 normal controls (p less than 0.001). Patients taking vitamin A supplements had significantly higher vitamin A concentrations than those not taking them (p less than 0.05), and hypercalcaemic patients had higher concentrations than normocalcaemic patients (p less than 0.005). Withdrawal of vitamin A supplements in seven patients caused significant falls in serum vitamin A concentrations and plasma calcium concentrations (p less than 0.01 at two and three months in both cases) and in plasma alkaline phosphatase concentrations (p less than 0.01 at two months). Vitamin A toxicity can contribute to hypercalcaemia in patients undergoing haemodialysis, probably by an osteolytic effect. Multivitamin preparations containing vitamin A should therefore be prescribed with caution in these patients.     

Bilateral eccentric and concentric torque of quadriceps and hamstring muscles in females and males

This study assessed maximum eccentric (ECC) and concentric (CON) torque of quadriceps (QUAD) and hamstring (HAM) muscle groups in healthy females (n = 13) and males (n = 27). Peak torques (PT) of bilateral muscle actions were recorded at constant angular velocities of 0.52, 1.57 and 2.61 rad.s-1. The QUADCON and HAMCON PT decreased (p less than 0.05) with increasing angular velocity. The QUADECC and HAMECC PT increased (p less than 0.05) in females, whereas QUADECC PT decreased (p less than 0.05) and HAMECC PT showed no change in males. In general, ECC PT was higher (p less than 0.05) than CON PT and QUAD PT was higher (p less than 0.05) than HAM PT, for any given angular velocity. Males displayed higher (p less than 0.05) PT than females but when PT were adjusted for body mass the sex differences in QUADCON and HAMCON were reduced (p less than 0.05), whereas the differences in QUADECC and HAMECC were abolished. The CON and ECC PT were, on average, 60% and 41% greater, respectively, in males than in females. The corresponding differences, when adjusted for body mass, were 23% and 8%. ECC:CON PT for QUAD were higher (p less than 0.05) in females than in males. CON and ECC HAM:QUAD PT ratio increased (p less than 0.05), as a function of velocity. This study suggests, that bilateral ECC PT is higher than CON PT and CON HAM:QUAD PT ratio is higher than ECC HAM:QUAD PT ratio.(ABSTRACT TRUNCATED AT 250 WORDS)