bluuebunny/crossref_metadata_2025 huggingface dataset:
Active transport of L-glucose and D-xylose in hamster intestine, in vitro
Authors: Bihler I. , Kim N. D. , Sawh P. C.
Published: April 2011

The mode of absorption of L-glucose and D-xylose was studied in vitro in preparations of hamster small intestine. Both sugars were actively transported from the lumen into the tissue when present at low concentrations. Their transport was Na+-dependent and was inhibited by ouabain, phlorizin, and competing sugars. Vmax for both sugars was Na+-independent and identical with that for many other monosaccharides. The apparent Km was only 5 times (D-xylose) or 8 times (L-glucose) less in the presence than in the absence of Na+(in contrast to 130 times for D-galactose). This explains why active transport is limited in extent and observable only at low concentrations. Countertransport was demonstrated with both these weakly transported sugars in the presence of strongly transported sugars, e.g. D-glucose, which explains the apparent secretion of L-glucose in the kidney in vivo. It is concluded that the mode of transport of L-glucose and D-xylose is identical with that of other sugars and consistent with a model proposed earlier.
The distribution of coenzyme Q in the tissues of the gravid ewe and fetus
Authors: Hidiroglou M.
Published: April 2011

Data on coenzyme Q tissue concentrations were obtained from 26 ewes and their fetuses from 50 days postconception to term. Coenzyme Q concentrations were low in early embryonic life. A significant increase was observed in coenzyme Q concentration in the 4-month-old or older fetal heart and kidney. The mean concentration of coenzyme Q in fetal liver increased also with advance in gestation but with less consistency than in the other tissues.
Effects of medroxyprogesterone acetate and chlorpromazine on ovulation and vaginal cytology in a strain of 4-day cyclic rats
Authors: Banik U. K. , Herr F.
Published: April 2011

A correlation observed between the vaginal cornification and the presence of freshly shed ova in the fallopian tube in a strain of 4-day cyclic rats was altered by administering medroxyprogesterone acetate (MPA) and chlorpromazine (CPZ). MPA, given 1 day before proestrus, blocked vaginal cornification, uterine fluid imbibition, and ovulation. A single injection of human chorionic gonadotropin (HCG), given on the expected day of proestrus, induced ovulation in all MPA-treated rats, but did not induce estrogenic parameters. CPZ, given at noon on the day of proestrus, also blocked ovulation, but did not alter the estrogenic effects. Again, HCG induced ovulation in CPZ-treated rats. These data indicate that MPA and CPZ have a similar pharmacologic effect at the hypothalamus–pituitary axis, while acting differently at the estrogenic receptor sites.
Serotonin and the plasma amino acid reduction caused by a single injection of growth hormone
Authors: Sirek O. V. , Niki A. , Niki H. , Sirek Anna
Published: April 2011

An acute reduction in the concentration of plasma free amino acids was observed in normal, hypophysectomized, pancreatectomized, and doubly operated (Houssay) dogs following a single injection of bovine growth hormone (NIH, lots B8, B12, and B13, 1–5 mg/kg). The reduction obtained with administered growth hormone in diabetic animals was abolished by dihydroergotamine (2 mg) or 2-brom-d-lysergic acid diethylamide (BOL-148, 1 mg). Pharmacological blockade of the adrenergic and serotonergic systems partially counteracted the growth hormone effect in normal and hypophysectomized dogs; complete suppression was achieved only in combination with puromycin (200 mg). These results indicate that the reduction in the concentration of plasma free amino acids following a single injection of growth hormone has at least two components. It is suggested that one is protein anabolic in nature and the other involves hepatic gluconeogenesis caused chiefly by serotonin.
Lobar blood flow and maturation of the fetal lamb lung
Authors: Chernick V.
Published: April 2011

In utero, hydrostatic gradients are expected to be absent and pulmonary perfusion to be uniformly distributed. However, the apical lobe of the fetal lamb lung is known to develop surfactant and functional stability before the basilar lobe. The present study was undertaken to determine whether lobar distribution of perfusion is uniform, as expected from hydrostatic considerations, or is nonuniform, reflecting the differences in the rate of maturation. The relationship between lobar growth and blood flow was studied in 15 fetal sheep ranging in gestational age from 115 days to term (147 days). Although lobe weight approximately doubled, the lobe weight/lung weight ratio remained uniform throughout the latter 20% of gestation. Relative lobar DNA concentration also remained uniform, suggesting that the rate of increase in cell number within each lobe was similar. The proportion of the superior vena caval return to the heart which perfused the fetal lung did not vary with gestation and averaged 7.8% ± 0.7. The distribution of pulmonary blood flow was intimately related to the relative distribution of cells (b = 1.02 ± 0.04; r = + 0.95; p < 0.001). Thus, the differential appearance of surfactant in fetal sheep cannot be explained by an increased substrate availability on the basis of nonuniform pulmonary perfusion. Pulmonary perfusion in utero is uniformly distributed, as would be expected from hydrostatic considerations.
Responses of young rats to an oral contraceptive fed with varying levels of pyridoxine
Authors: Beare-Rogers Joyce L. , Rogers C. G. , Sabry Z. I.
Published: April 2011

The oral contraceptive preparation Enovid was fed to female rats with 0, 0.5, 1.0, or 10 μg of pyridoxine per gram of diet. Except with the pyridoxine-deficient diet, the hormonal treatment produced lower body weights than were found in the corresponding pair-fed rats. Enovid did not appear to aggravate the condition of the pyridoxine-deficient animals. The elevated levels of urinary xanthurenic acid, inversely related to the dietary intake of pyridoxine, were depressed by the estrogen–progestogen preparation. Although Enovid did not alter the total amount of liver vitamin B6, it seemed to stimulate the alanine aminotransferase in the liver, and to elevate inconsistently that enzymic activity in erythrocytes. Aspartate aminotransferase in erythrocytes and liver appeared to be unaffected by the hormonal treatment.
On a possible mode of action of the gonadotrophin-inhibiting factor (GIF) of human male urine
Authors: Cooper Ted
Published: April 2011

The present series of experiments confirm the presence of a gonadotrophin-inhibiting factor (GIF) in human male urine. This factor inhibits the response of the immature mouse uterus to stimulation by luteinizing hormone (LH) or small doses of estradiol (E2). It is known that the presence of the vitamin folic acid is essential before the uterine response to estrogen can be demonstrated. Experiments are described showing that folic acid (PGA) per se will not protect the uterus from the inhibiting action of GIF, but that its reduced form (FH4) will. It is possible that GIF interferes with dihydrofolate reductase, the enzyme responsible for the reduction of PGA to FH4.
Modified solid-phase (tube) radioimmunoassay of human growth hormone
Authors: Bala R. M. , Ferguson K. A. , Beck J. C.
Published: April 2011

Polystyrene tubes were coated with rabbit antiserum to human growth hormone (HGH). Bovine serum albumin (BSA) in buffer, HGH standard or unknown samples, and 125I-HGH were added to the antibodycoated tubes. After incubation the radioactivity in each tube was counted, the incubate discarded, the tubes were washed, and radioactivity was recounted. The sensitivity of the assay was consistently 0.05 mμg HGH or less. Nonspecific binding by uncoated tubes was less than 1%. It was preferable to control the surface area exposed to excess antiserum rather than limit the concentration of the antiserum. Polypropylene and polystyrene tubes gave similar results. Variation of ionic composition or pH of the incubate had no significant effects. Maximum precision and sensitivity occurred with incubation at 4 °C for 40 to 60 h. Addition of posthypophysectomy human plasma or varying the protein concentration had similar effects. The immobilized antibody may be more selective in binding with antigen than is free antibody in solution. Our modifications combine favorable features of the solid-phase system with an increase in sensitivity and greater economy of materials.
The effects of anoxia, glucose, ATP, and ouabain on Na, K, and Cl in the rabbit lens
Authors: Matuk Y. , Manery J. F. , Dryden E. E.
Published: April 2011

Rabbit lenses were incubated at 37 °C in Tyrode's solution which was aerated either with 95% O2 + 5% CO2 or with 95% N2 + 5% CO2. The Na, K, Cl, and water concentration in each lens was determined after the incubation period. A procedure was developed for oxidizing the sulfhydryl groups in the lens so that a semimicro, electrometric method for the determination of Cl could be used. The data showed that anoxia alone produced a decrease in K and an increase in Na and Cl. These electrolyte shifts were prevented by the addition of glucose (200 mg%) or ATP (10−3 M) to the bathing medium. When ouabain (10−6 M) was also added neither glucose nor ATP were effective in preventing the electrolyte changes induced by anoxia. These results permit three conclusions: (1) the electrolyte concentration of the lens can be supported by aerobic and anaerobic metabolism; (2) anaerobic metabolism of added glucose can prevent downhill movements of Na and K; and (3) exogenous ATP can also be utilized by the lens to prevent downhill movements of the cations.
Fibrinolytic activities of euglobulins precipitated at pH 6.4, 6.0, and 5.3
Authors: Hedlin A. M. , Monkhouse F. C.
Published: April 2011

As a result of problems encountered with euglobulin preparation at pH 5.3, a study was undertaken to determine the pH level that provided the best recovery of fibrinolytic material. The euglobulin lysis test was used to measure the difference in activity at each pH level. Euglobulins were prepared from rabbit plasma at pH 6.4, 6.0, and 5.3, subjected to a variety of treatments, and separated on a DEAE cellulose column. Samples were assayed for plasminogen, plasmin, fibrinogen, prothrombin, and antithrombin levels. Results indicated the presence of plasminogen and plasmin at all three pH levels, with the greatest specific activity in the pH 6.0 and 5.3 euglobulins precipitated from defibrinated, urokinase-activated plasma. Maximum total activity was found in the pH 6.0 euglobulins. Approximately 25% of the plasma fibrinogen was precipitated at the pH 5.3 level. Trace amounts of prothrombin were found at all three pH levels. No measurable antithrombin was found in any of the samples. It was concluded that, of the three pH levels studied and with a two-stage euglobulin lysis test, the pH 6.0 precipitation provided the best measure of change in the fibrinolytic system.
The effect of cortisone on brown adipose tissue of young rats
Authors: Hahn P. , Drahota Z. , Skala J. , Kazda S. , Towell Molly E.
Published: April 2011

Rats aged 7 to 9 days were injected for 1 to 3 days with 5 mg/100 g body weight cortisone acetate per day. This led to an increase in the weight of brown adipose tissue, an increase in its fat content, and a decrease in its protein content. The content of norepinephrine in brown adipose tissue was decreased by cortisone treatment. The in vitro increase in O2 consumption following the addition of 5 μg nore-pinephrine/ml in vitro to brown adipose tissue from control animals was abolished by cortisone administration. Lipolysis due to norepinephrine was, however, not affected and was even slightly increased in cortisone-treated rats. Mitochondrial succinate–tetrazolium reductase activity was decreased after treatment with cortisone. It is concluded that cortisone alters the mitochondria of brown adipose tissue but has little effect on lipolysis as such. The content of norepinephrine in brown adipose tissue was found to decrease immediately after birth and then to return rapidly to higher levels.
Site of action of endotoxin in evoking bradycardia
Authors: Blattberg B. , Levy M. N.
Published: April 2011

Previous investigation of the mechanism responsible for the bradycardia evoked by the intravenous injection of bacterial endotoxin revealed that the primary site of action of the endotoxin must be some subdiaphragmatic structure. The present study was undertaken to localize more precisely this site of action. In anesthetized dogs, the renal pedicles or the intestinal arteries were ligated before endotoxin was administered. It was found that exclusion of the intestinal vascular bed prevented the fall in heart rate, whereas occlusion of the renal vasculature did not alter the cardiac response. To localize the mesenteric site of action of endotoxin more precisely, small doses of endotoxin were injected into each of the individual intestinal arteries and into the splenic artery and the portal vein. The response was compared with that evoked by the injection of an equivalent amount of endotoxin into a femoral artery. It was observed that when endotoxin was injected into the intestinal arteries, bradycardia resulted. However, when endotoxin was injected into the femoral artery or the portal vein, no significant change in heart rate was detected, indicating that the intestines probably are the site of action for evoking bradycardia.
Tissue temperature gradients in the African guinea hog
Authors: Kuehn L. A. , Livingstone S. D. , Topliff E. D. L.
Published: April 2011

Tissue temperature gradients were measured in the front leg, rear leg, back, and rump of the African guinea hog and were fitted to a parabolic model. The depth at which the estimated temperature became equal to the rectal temperature was constant regardless of ambient temperature (in the range −1.1 °C to 37.8 °C).
New assay of fibrinolytic activity as a continuous rate reaction
Authors: Roschlau Walter H. E. , Miller Sandra L.
Published: April 2011

A new and rapidly performed in vitro assay of fibrinolytic activity, incorporating turbidimetric measurements of fibrin suspension substrate, is described. The assay allows the write-out of rate reactions by recording the changes in light transmittance through a sample of substrate while it is subjected to enzymatic degradation by fibrinolytic agents. By running the reaction in buffer or serum, the properties of plasminogen activators can be differentiated from those of proteolytic enzymes. Data obtained with this method allow the estimation of relative potencies, quantitative inhibition of enzymes by serum, rate of plasminogen activation, etc., for which examples are given.
Effect of chronic administration of insulin on pituitary gland content of growth hormone in the normal rat
Authors: Hazelwood Robert L. , Galaznik John G.
Published: April 2011

Acetone-dried pituitary glands from young adult female rats (starting weight 165–168 g) previously injected (s.c.) with doses of insulin of 0.5 U to 1.0 U/kg body weight for 4 days, and then with 2.0 U/kg 6 days a week for an additional 34 days, were bioassayed in young hypophysectomized rats for growth hormone content. Insulin-injected rats gained significantly more weight than saline-injected controls. The tibia cartilage width of the insulin-injected donor rats was greater than that of control rats after 9, 17, 24, and 31 days of insulin; pituitary gland preparations from these insulin-injected rats increased tibia cartilage widths slightly but significantly over those of rats injected with control pituitary gland preparations.
Effect of an oral contraceptive on spontaneous running activity of female rats
Authors: Fregly M. J. , Hughes R. E. , Cox C. E.
Published: April 2011

Dietary administration of Enovid® at 7.5 mg/kg of food for 11 days to intact female rats reduced their cyclic running activity and induced changes in vaginal cytology characteristic of estrus. There was a linear relationship between the logarithm of the dose of Enovid® ingested and the percent decrease in running activity from the average observed before drug administration. Dietary administration of norethynodrel, one of the two components of Enovid®, at 7.5 mg/kg of food for 21 days decreased the magnitude of the running activity slightly but failed to affect its cyclic nature. In contrast, dietary administration of mestranol at either 0.125 or 0.54 μg/kg of food for 24 and 29 days respectively reduced running activity and increased the length of the estrus cycle. Hence, the effect of Enovid® on the running activity of intact rats is probably attributable to the mestranol contained in it. An apparent escape from the effects of chronic administration of mestranol on spontaneous running activity was observed from 20 to 30 days after beginning treatment with either dose used. The escape was characterized by a reinitiation of cyclic running activity during chronic drug administration. Elucidation of the mechanism of the escape phenomenon will require further study.
Potentiation of norepinephrine-induced activation of cardiac phosphorylase by theophylline and reserpine
Authors: McNeill John H.
Published: April 2011

Reserpine and theophylline pretreatment significantly enhanced the norepinephrine-induced activation of rat cardiac phosphorylase a activation as shown by a shift to the left in the norepinephrine dose–response curve. When both treatments were administered together the curve was shifted further to the left. The results indicate that reserpine and theophylline probably enhance the norepinephrine response by different mechanisms.
The influence of size and shape of kidney tissue from newborn and mature rats on the uptake of amino acid
Authors: Webber William A.
Published: April 2011

The uptake of alpha-aminoisobutyric acid was studied in kidney cortical tissue of newborn and mature rats in the light of observations that the size and shape of the tissue pieces could influence concentrating ability. It was found that the pattern of differences in uptake by newborn and mature tissue was not altered by differences in the size and shape of tissue pieces. The initial uptake was more rapid in mature tissue but a higher maximum concentration gradient was ultimately achieved by newborn tissue. However, there was a difference in the maximum gradient achieved by newborn tissue depending on the configuration of the pieces of tissue incubated, and it is important, therefore, to know the morphology of the tissue being studied in interpreting the results of incubation studies.
Gastric hyposecretion produced in rats by long-term oral administration of glycopyrrolate
Authors: Kowalewski K. , Schier J.
Published: April 2011

An anticholinergic drug, 1-methyl-3-pyrrolidyl-2-phenylcyclopentaneglycolate methobromide (glycopyrrolate) dissolved in drinking water, was given to the rats. The treatment lasted for 5 months. A secretion study was then performed in gastric fistula-bearing animals, infused for 24 h with normal saline or histamine. A significant decrease of the secretory function of parietal and zymogenic cells was found in treated rats, as compared with untreated control animals. Long-term administration of an anticholinergic drug in drinking water appears to be an easy experimental method of induction of gastric secretory hypofunction in rats.
Effects of various selenium compounds on the development of muscular dystrophy and other vitamin E dyscrasias in the chick
Authors: Jenkins K. J. , Dickson R. C. , Hidiroglou M.
Published: April 2011

Selenite, selenate, selenodicysteine, selenocystine, and selenomethionine, when administered orally, provided comparable protection against the development of nutritional muscular dystrophy in chicks fed a vitamin E deficient fat-free diet. When unsaturated lipid was included in the tocopherol-deficient basal ration, many of the control chicks not receiving selenium developed exudative diathesis as well as muscular dystrophy. Supplementation with either selenoamino acids, selenite, or selenate completely prevented exudates and provided the same degree of protection against muscle degeneration as obtained with the fat-free diet. Unexpectedly, however, when lard was fed, supplementation with selenite or selenate (but not the selenoamino acids), while alleviating exudates and dystrophy, provoked the onset of encephalomalacia.
The electrical and mechanical response of rat papillary muscle to paired pulse stimulation
Authors: Lee S. L. , Mainwood G. W. , Korecky B.
Published: April 2011

Myocardial fibers in rat papillary muscle preparations are electrically reexcitable 60 ms or less after previous excitation. Electrical reexcitation at this early stage has no mechanical counterpart and does not increase peak tension, area under the tension curve, or dT/dt. When the isometric tension response to a paired stimulus is superimposed upon the isometric tension response to a single stimulus, no differences in the shape or amplitude of the curves can be detected while the pulse interval is less than 80 ms. As the paired pulse interval is increased beyond 80 ms a small additional response to the second pulse is seen, superimposed upon the response to the first. The response to the second pulse increases progressively as the pulse interval is increased. The increase in response with increasing pulse interval was used to plot the time course of recovery. Recovery is accelerated by epinephrine and decreased by low calcium. The evidence suggests that the limiting factor in the recovery process is in the excitation–contraction coupling system. It is postulated that the recovery of the coupling system depends upon the recharging of the 'rapidly releasable' calcium fraction within the fiber which is completely discharged by the triggering action of a single action potential.
The effect of shifts in the dietary amino acid pattern on feed consumption in the chick
Authors: March B. E. , Walker Ruthven O.
Published: April 2011

The rate at which feed consumption responds to alteration of the lysine level in the diet was studied. The basal diet was a lysine-deficient corn–sesame diet which was fed with and without lysine supplementation. Chicks were fed the two diets alternately in three experiments. Feed consumption was increased or decreased within 6 to 8 h of altering the lysine content of the diet. Sensitivity to the dietary lysine level was lower in birds maintained at 15.5 °C than in birds at 26.6 °C. It is suggested that the increase in body temperature previously reported to occur when a lysine-deficient diet is fed to chicks is the metabolic response leading to depression of feed consumption.
Preservation of immunological and biological activities of insulin by insulinase inhibitor in vitro
Authors: Pierluissi J. , Campbell J. , Rastogi K. S. , Green G. R. , Lazdins V.
Published: April 2011

The relation of insulinase activity to the biological effect of insulin on isolated tissue was studied. Rat diaphragm in vitro caused the rapid disappearance of immunoreactive insulin (IRI) in physiological concentrations. IRI loss at time intervals was exponential. The fractional rate of loss of IRI was therefore independent of IRI concentration and was also approximately constant per milligram of tissue, the value being 0.0216%/mg∙mm. The value of the Michaelis constant (Km), obtained from initial velocities at five initial concentrations of IRI, was 1.85 × 10−8M, and of the maximal velocity (Vmax) was 2.32 × 10−11 mole/g∙min, based on insulin dimer. The addition of an insulinase inhibitor (a partial hydrolysate of insulin) to hemidiaphragm in vitro reduced the fractional rate of IRI loss by 60%. The increase in Km, without appreciable change in Vmax, indicated that the inhibition was competitive. The IRI preserved by means of the inhibitor was biologically active, since it increased the glycogen accumulation and the incorporation of 14C-U-glucose into glycogen in a second, fresh hemidiaphragm. In single incubation of hemidiaphragm with insulin, the gain in glycogen was correlated with the amount of inhibitor. The biological effect of insulin on diaphragm in vitro was therefore limited by tissue insulinase activity, and insulinase inhibitor potentiated to some extent the action of insulin.
Inhibition of exocrine pancreatic secretion by glucagon and D-glucose given intravenously
Authors: Nakajima Sumio , Magee D. F.
Published: April 2011

The actions of glucagon and D-glucose on blood glucose and exocrine pancreatic secretion in response to secretin were studied in unanesthetized dogs with chronic pancreatic fistulas, gastric fistulas, and a gastroenterostomy which diverted gastric acid from the duodenum. Both glucagon and D-glucose, when given intravenously, produced significant and dose-related inhibition of the volume of pancreatic secretion and of the protein, amylase, lipase, and protease outputs. There was a linear inverse relationship between pancreatic enzyme output and blood glucose levels following glucagon or D-glucose infusion. Statistical analysis of the data showed that the slopes of the lines relating blood glucose to amylase, to lipase, and to protease were significantly different from each other, indicating preferential inhibition for amylase.
Cardiovascular adaptation of newborn lambs to hypervolemia with polycythemia
Authors: Fouron Jean-Claude , Hébert Francine
Published: April 2011

Hemodynamic studies were carried out in five newborn lambs before, during, and for a period of 3 h after an increase of approximately 50% in blood volume. Four other animals served as a control group. The animals were delivered by cesarean less than 1 week before the anticipated date of birth. Pressures were continuously recorded in aorta, pulmonary artery, and right and left atrium. Pulmonary and systemic flows as well as the possible shunts through the ductus arteriosus and the foramen ovale were calculated according to the Fick principle. The results showed a marked increase in systemic flows, followed by a progressive reduction but no return to the base-line level, closure of the ductus arteriosus during or shortly after the infusion, and a transient systemic and pulmonary hypertension associated with a marked elevation in left and right atrial pressures. No change was observed in the cardiac rhythm or the O2 consumption. These data suggest that the venous vascular bed of newborn lambs is less able than that of adult animals to cope with an acute increase in blood volume.
The area and volume of single human erythrocytes during gradual osmotic swelling to hemolysis
Authors: Canham Peter B. , Parkinson David R.
Published: April 2011

A double-chambered slide was designed for the microscope which would enable continuous viewing of cells hanging on edge in a Ringer solution which was gradually being reduced in osmotic pressure. This was achieved by putting a dialysis membrane between the cell chamber and a chamber containing distilled water. Photographs were taken at 1-min intervals of single cells on edge (revealing the biconcave profile) until the cells hemolyzed, usually within 30 min. The area and volume of revolution of each cell were calculated from measurements on photographic enlargements. No significant change in area occurs during the swelling series although the red cell changes gradually from biconcave to spherical and remains spherical for approximately 7 min before hemolyzing. This stability is best explained by a leakage of potassium ion from the cell prior to hemolysis (which has been reported by Seeman to be approximately 20%).
Factors affecting the contractile responses of the rat vas deferens to cocaine and tetracaine
Authors: Vohra M. M.
Published: April 2011

Pretreatment of the rats with 10 mg/kg of reserpine for 18–20 h abolished the responses to cocaine; the responses to transmural stimulation were reduced but not abolished. Addition of small quantities of guanethidine to these reserpine-treated preparations resulted in complete abolition of responses to transmural stimulation. The catecholamine stores of the rat vas deferens seem to be relatively resistant to the depleting actions of reserpine. These results indicate that the contractile responses of the rat vas deferens to cocaine are mediated through the release of endogenous catecholamines. An increase in the pH increased the responses to both cocaine and tetracaine, and a decrease in the pH decreased their contractile responses. Although the nonionized form of these local anesthetics seems to be essential for their action, the active molecular species responsible for eliciting contractions of the vas deferens remains unsettled. It is possible that a variation in pH might account for the divergent actions reported for these agents by earlier investigators.
The effect of heart rate on the content of calcium in a pool associated with the maintenance of contractile force
Authors: Bailey L. E. , Downie J. W.
Published: April 2011

We investigated the effect of heart rates of 60, 120, and 240/min on several parameters in the cat heart. These were the uptake and content of Ca in a pool in the myocardium associated with the maintenance of contractile force, CaII; the rate of perfusion of the heart during washout; the half-times for the washout of CaII; and the force of contraction. An increase in heart rate from 60 to 120/min caused a significant increase in the uptake of Ca into CaII. The amount of Ca taken up by CaII was not further increased at a heart rate of 240/min. The half-times for the washout of CaII were related directly to the heart rate. These observations confirm that the uptake of Ca by the heart is directly related to heart rate and show further that the Ca is taken up by CaII.
Dose–response effects of cardiac glycosides on pooling and systemic and pulmonary hemodynamics
Authors: Archer Linda T. , Hinshaw Lerner B.
Published: April 2011

The effects of ouabain and digoxin on systemic and cardiopulmonary circulations and the degree and site of vascular pooling were evaluated in this study. A major emphasis was placed on the relationship of dosage to responses observed. Experiments were performed on 32 adult mongrel dogs using a venous return (constant cardiac inflow) preparation. Animals were divided into two groups, intact and eviscerated. Mean cumulative doses were 27, 55, and 81 μg/kg for intact ouabain-injected dogs; 21, 42, 63, 84, and 105 μg/kg for intact digoxin-injected dogs; and 26, 52, and 77 μg/kg for eviscerated ouabain-injected dogs. There was a positive correlation between amount of blood pooled and dose of cardiac glycosides given in the intact animal. The statistical difference in pooling at each dose of ouabain between intact and eviscerated animals implicated the hepatosplanchnic vascular bed as a major site of pooling. Since there was a significant statistical increase in total peripheral resistance in intact ouabain-injected dogs but not in ouabain-treated eviscerated animals, the site of peripheral resistance changes appears to be the hepatosplanchnic vascular region. Left atrial pressures rose significantly in intact and eviscerated dogs at higher ouabain doses. These findings underscore the complexity of the mechanisms of action of cardiac glycosides and emphasize the critical importance of dosage, type of glycoside administered, and individual variation of response in the canine species.
Additional studies on penicillin-induced stimulation of renal PAH transport
Authors: Hirsch G. H. , Hook J. B.
Published: April 2011

Treatment of nursing rats with penicillin significantly increased p-aminohippurate (PAH) transport in renal cortical slices from these animals, but had no effect on tetraethylammonium (TEA) transport. Addition of acetate had a similar stimulatory effect on PAH transport in renal cortical slices from both penicillin-treated and control nursing rats. Although penicillin treatment of nursing rats enhanced the accumulation of PAH by renal cortical slices, the rate of PAH entry into the tissue was not significantly increased. When pregnant rabbits were treated with penicillin during the last half of pregnancy, PAH transport was significantly increased in renal cortical slices from the treated fetuses. The effect of penicillin on PAH transport appears to be reversible since the significant increase in PAH transport observed 24 h after treating 2-week-old rabbits for 3 days was no longer observed when PAH uptake was determined 8 days after discontinuing penicillin treatment. The data support the hypothesis that the stimulatory effect of penicillin on PAH transport is due to substrate stimulation of the active concentrating mechanism mediating PAH secretion. Acetate is suggested to act at an additional step in the secretory process.
The effects of atropine, pralidoxime, and lidocaine on nerve–muscle and respiratory function in organophosphate-treated rabbits
Authors: Johnson D. D. , Stewart W. C.
Published: April 2011

Death due to poisoning with organophosphate cholinesterase inhibitors has been attributed to central respiratory depression or to a combination of the central effects and peripheral neuromuscular blockade. Atropine has been reported to be an effective antidote against the central respiratory depression. Pralidoxime and lidocaine will reverse some of the peripheral manifestations of organophosphate cholinesterase inhibitors. Experiments were performed on rabbits to measure the effectiveness of atropine alone or in combination with pralidoxime or lidocaine in reversing the changes produced in neuromuscular and respiratory function by the administration of sarin. Atropine alone will reverse the respiratory arrest produced by sarin without affecting the changes in nerve–muscle function. In the presence of atropine, pralidoxime will reverse all of the peripheral manifestations of cholinesterase inhibition as well as the respiratory arrest produced by sarin administration. Lidocaine will abolish twitch potentiation produced by sarin but enhances the respiratory depression. Respiratory arrest produced by the combination of sarin and lidocaine is reversed by atropine.
Uptake of 2,6-diaminopurine-2-14C by 2,6-diaminopurine-sensitive and -resistant L strain mouse cells grown on plastic discs
Authors: Blair D. G. R. , Hebert G. J.
Published: April 2011

The short-term uptake of 2,6-diaminopurine-2-14C by 2,6-diaminopurine-sensitive (DAP-s) or -resistant (DAP-r) L cells was studied by means of a "disc sampling" technique. Monolayers of cells were grown on plastic discs which were subsequently incubated for various periods of time in cell growth medium containing 2,6-diaminopurine-2-14C. At 37 °C the uptake of DAP-2-14C by DAP-r cells was relatively linear with respect to the extracellular concentration of DAP-2-14C, whereas the uptake by DAP-s cells was characterized by the phenomenon of saturation. The uptake of DAP-2-14C by DAP-s cells was greatly reduced by lowering the temperature to 4 °C, and a Q10 value of 1.8 was calculated. Under conditions of low temperature and (or) short incubation time, which limited DAP metabolism in DAP-s cells, the uptake of DAP-2-14C by DAP-s and DAP-r cells was similar, suggesting similar permeability. However, the involvement of an enzymatic transport system, as well as the intracellular metabolic enzyme system, in DAP-s cells was not ruled out. The data suggest that permeability is not a major factor in the resistance of L cells to DAP, but the overall uptake of DAP is facilitated by the presence in DAP-s cells of adenine phosphoribosyltransferase, which catalyzes the formation of DAP ribonucleotide, and possibly of an enzymatic transport system, whereas the entry of DAP into DAP-r cells, which lack, or have very low amounts of, adenine phosphoribosyltransferase, appears to be by simple diffusion.
A nomogram for calculation of the wet bulb – globe temperature index
Authors: Kuehn L. A. , Stubbs R. A. , MacHattie L. E.
Published: April 2011

A device is described that facilitates the calculation of the wet bulb – globe temperature index. It consists of a small nomogram on which two scales, representing the dry bulb temperature, the natural wet bulb temperature, and the globe temperature, are inscribed so that reference to these scales with two movable cursors results in computation of the WBGT index at a third scale.
Uptake and Transport of Pesticidal Carbamates by Everted Sacs of Rat Small Intestine
Authors: Pekas J. C.
Published: April 2011

The absorption of five 14C-labeled pesticidal carbamate chemicals was studied using everted sacs of rat small intestine after verification that the technique of preparation and incubation of the sacs allowed consistent active transport of 14C-glucose. All five carbamates (4-chloro-2-butynyl N-(3-chlorophenyl)carbamate, 1; isopropoxyphenyl N-methylcarbamate, 2; 4-benzo-thienyl N-methylcarbamate, 3; 1-naphthyl N-methylcarbamate, 4; and 4-dimethylamino-3,5-xylyl N-methylcarbamate, 5) underwent some autodegradation during incubation in Krebs–Ringer bicarbonate medium. Carbamates 3 and 5 were the most unstable. When each of the 14C-carbamates was placed only in the mucosal fluid, a mixture of radiolabeled carbamate and degradation products was recovered from the serosal fluid. When the initial carbamate concentration (10−5 M) in the mucosal and serosal fluids was the same, there was a net increase in the total 14C concentration (14C-carbamate plus 14C-products) of the serosal fluids for carbamates 2 and 3 (and possibly 1) as follows: A net mucosal to serosal transport occurred in sacs derived from the caudal intestine for carbamates 1 and 3, and in sacs from the middle intestine for 2. Substantial tissue uptake of 14C occurred, particularly by those sacs which accomplished a net mucosal to serosal transport.
Dietary DL-Methionine and Rat Liver Arginase Activity
Authors: Acheampong-Mensah D. K. , Hill D. C.
Published: April 2011

Addition of 4.0% of DL-methionine to a diet based on 10% casein as the protein source markedly increased the concentration of hepatic arginase in weanling rats, but did not affect the total amount of the enzyme or urea excretion. Essentially the same effects were obtained by restricting the food intake of the control group to that of the high-methionine group. Supplementation of the high-methionine diet with 4.0% of glycine decreased the concentration of hepatic arginase, but did not affect the total amount. The data indicate that the effect of methionine on the concentration of liver arginase is secondary to its effect on food intake.
Effect of Oxygen on Tissue Temperature Gradients in the African Guinea Hog
Authors: Livingstone S. D. , Kuehn L. A. , Topliff E. D. L.
Published: April 2011

African guinea hogs (Sus scrota, miniature variety) were exposed to an ambient temperature of 10 °C for 100 min. Temperatures at various depths in the rump were measured and the depth at which tissue temperature became equal to rectal temperature was calculated. It was found that breathing 100% oxygen increased this depth relative to the depth when air was breathed.
Biphasic Response of the Transmurally Stimulated Rat Duodenum
Authors: García-Rodríguez M. , Menéndez-Cepero E. , Saínz-Guevara F. , Díaz J. M. Reyes
Published: April 2011

Transmural electrical stimulation of the isolated rat duodenum preparation produced a relaxation followed by a contraction. The first phase seems to be due to the liberation of an inhibitory substance. It is unaffected by bretylium, bethanidine, phentolamine, and propranolol, but abolished by the previous treatment of the rat with reserpine. Hexamethonium does not affect this initial relaxation. The second (contractile) phase seems to be due to the liberation of an acetylcholine-like substance, because it is greatly decreased and sometimes abolished by atropine. Both phases are abolished by cocaine.
Supraesophageal Ganglia Influences on Limulus Heart Rhythm: Confirmatory Evidence
Authors: Corning W. C. , Lahue R. , Burg R. Von
Published: April 2011

The supraesophageal ganglia of Limulus are capable of exerting a strong, phasic, inhibitory effect on heart rate. Stimulation at low frequencies was found to produce a transient inhibition of rate. This effect was mediated by dorsal nerves 7 and 8 emerging from the postesophageal ganglia. Since these nerves are inhibitory in function, it is suggested that the Limulus brain may exert its inhibitory effect on heart rate by providing an excitatory drive of cardioinhibitors lower in the system. The results of various lesions showed that a split of the supraesophageal ganglia produces a transient, moderate cardioacceleration indicating a weak tonic influence of the brain. A bilateral removal had no significant effects on rate. The possibility of opposing sets of function in Limulus brain is discussed.
The Effect of Acute Ethanol Administration on Parathion Toxicity and In Vitro Parathion Degradation in the Rat
Authors: Villeneuve D. C. , Phillips W. E. J.
Published: April 2011

Both the oral and intraperitoneal administration of acute doses of ethanol resulted in decreased toxicity of parathion in the rat. The rate of in vitro parathion degradation by liver homogenates from rats administered ethanol by the oral route was lower than in the control rats. These results indicate that the altered toxicity is not due to enzyme induction.
Effects of Single Cortisone Injections on Brown Adipose Tissue of Developing Rats
Authors: Skala Josef , Hahn Peter
Published: April 2011

An injection of a single dose of cortisone acetate (5 mg/100 g body weight) to 9-day-old rats resulted in the following changes in brown adipose tissue 24 h later: (1) the fresh weight was increased due to fat accumulation; (2) the DNA content of whole interscapular brown fat stayed unaltered, while the RNA content was increased; (3) specific activities of cytoplasmic alpha-glycerophosphate dehydrogenase and malic enzyme were increased; (4) the percentage of mitochondrial protein in the whole tissue protein was not changed, but mitochondria seemed to be more fragile, fewer were recovered by a standard isolation procedure, and more cytochrome c oxidase contaminated the microsomal fraction; (5) mitochondrial alpha-glycero-phosphate dehydrogenase and succinate dehydrogenase activities were decreased per milligram homogenate protein and (in isolated mitochondrial fraction) per milligram mitochondrial protein; (6) the endogenous respiration of brown fat mitochondria was activated much less by carnitine and CoA; and (7) CO2 formation from palmitate-14C by isolated mitochondria was considerably lower.A similar injection to 30-day-old rats had no significant effect.It is suggested that a single injection of cortisone affects the mitochondrial structure of brown adipose tissue and the ability to oxidize fatty acids and that it is effective on day 10 but not on day 30.
Comparative Metabolim of Chlorobenzilate, Chloropropylate, and Bromopropylate Acaricides by Rat Hepatic Enzymes
Authors: Knowles Charles O. , Ahmad Sami
Published: April 2011

Chlorobenzilate (ethyl 4,4′-dichlorobenzilate), chloropropylate (isopropyl 4,4′-dichlorobenzilate), and bromopropylate (isopropyl 4,4′-dibromobenzilate) were metabolized by rat liver preparations, with the microsomal and the nuclear supernatant fractions being most active. The limiting reaction was cleavage of the ester linkage by carboxylesterases, which showed greater activity for the ethyl ester (chlorobenzilate) than for the isopropyl ester (chloropropylate and bromopropylate). This initial reaction was blocked by the organophosphate DFP (diisopropyl phosphorofluoridate). SKF-525A enhanced to some extent the degradation of chlorobenzilate by the mitochondrial and possibly the microsomal fractions. p-Chlorobenzoic acid from chlorobenzilate and chloropropylate and p-bromobenzoic acid from bromopropylate were the identified end products of acaricide metabolism by the hepatic enzymes.
Tissue Selenium Concentrations in Sheep Fed a Purified Diet
Authors: Buchanan-Smith J. G. , Sharp B. A. , Tillman A. D.
Published: April 2011

Ewes fed a protein-free purified diet were treated with vitamin E or selenium, separately or in combination, and were sacrificed at intervals during their first gestation, having been fed the diet for an average of 240 days. Selenium treatment significantly increased tissue concentrations of the element three- to thirty-fold. Vitamin E administration had no consistent effect on tissue selenium levels. A low level of dietary selenium (0.005 p.p.m.) was associated with low tissue levels of selenium (0.03–0.4 p.p.m., wet basis) in the sheep treated with vitamin E only. This result suggests that the purified diet used, in this experiment may be suitable for selenium deficiency investigations in ruminants.
Continuous Measurement of Variations of in Peritoneal Fluid
Authors: Harichaux P. , Freville M. , Lienard J. , Denoeux J. P. , Bonn G.
Published: April 2011

A technique is presented for continuous recording of [Formula: see text] of peritoneal fluid. It was shown that there was no difference in the utilization of different kinds of solutions in regard to the changes in [Formula: see text]. [Formula: see text] changes occurred more rapidly than ionic changes. Assisted ventilation rapidly modified [Formula: see text] levels in peritoneal fluid.
The Metabolism of Chlorpromazine by Developing Rabbit Liver
Authors: Bhatnagar S. P.
Published: April 2011

The developmental pattern of various metabolic pathways involved in the detoxification of chlorpromazine was investigated in rabbits by employing hepatic microsomal enzyme preparations and the isolated perfused liver technique. The sulfoxidation and hydroxylation at position 7 of the phenothiazine ring and mono- and di-demethylation of the aliphatic side-chain of sulfides, sulfoxides, and the hydroxylated derivatives constituted the principal metabolic pathways in adult animals, as characterized by thin-layer chromatography. The activity of 3-day-old liver was limited to the sulfoxidation, hydroxylation, and mono-demethylation of the parent compound while fetal liver, 4 days before term, could only effect the sulfoxidation reaction. The transformation in fetus and neonate appeared to progress better when the livers were perfused with whole blood under physiological conditions. Phenobarbital pretreatment accelerated the formation of various metabolites by both the adult and neonatal livers but not by the fetal livers. The stimulatory effect was completely abolished by in vivo administration of DL-ethionine. SKF 525-A caused a substantial in vivo and in vitro inhibition of the drug-metabolizing activity, regardless of the phenobarbital pretreatment.
Responses to Noradrenaline and Potassium, and Disposition of Noradrenaline in Aortic Strips of Desoxycorticosterone Acetate – NaCl Hypertensive Rabbits
Authors: Kalsner Stanley , Ayitey-Smith Edward , Ling George M.
Published: April 2011

The responses of aortic strips to low concentrations of noradrenaline (3 × 10−10, 1 × 10−9, and 3 × 10−9 g/ml) were enhanced in rabbits made hypertensive by desoxycorticosterone acetate (DOCA)–NaCl. However, contractions of equivalent magnitude produced by potassium were depressed. No augmentation of responses to noradrenaline was observed if the strips were maintained under 5 rather than the standard 2 g tension. Experiments utilizing the oil-immersion technique, to eliminate diffusion of drug into the bathing medium, revealed that there was no difference in the ability of aortic strips from normotensive and hypertensive rabbits to inactivate noradrenaline (1 × 10−8 g/ml). Also, the role of catechol-O-methyl-transferase in terminating the action of this amine did not differ in strips obtained from untreated and DOCA–NaCl treated rabbits. It is concluded that enhanced responses of aortic strips to noradrenaline in hypertension are not explicable on the basis of an alteration in amine metabolism.
Measurement of Input Impedance and Cytoplasmic Resistivity with A Single Microelectrode
Authors: Schanne Otto F. , Ceretti Elena R. P. de
Published: April 2011

A square pulse analysis of the transient, recorded through a microelectrode impaled in a biological cell, yields its input impedance in series with the microelectrode resistance. Calibration of the microelectrode in solutions of different resistivities allows the direct measurement of cytoplasmic resistivity. Measurements in frog sartorius gave results comparable to those reported in the literature.