bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of cyanide and dinitrophenol on membrane properties of single nerve fibers
Authors: Schoepfle Gordon M. , Bloom Floyd E.
Published: December 2017

Exposure of frog single nerve fibers to cyanide or to dinitrophenol results in a decline in spike height without change in either the resting membrane potential or in the maximal limiting response obtained during strong hyperpolarization. Effects of cyanide are completely reversible; those of dinitrophenol, only partially so. These data are taken to indicate that cyanide depresses the steady state level of the sodium conductance h factor before it produces any appreciable change in either the sodium or potassium equilibrium potentials as a result of interference with the metabolically linked sodium-potassium exchange mechanism. Strong hyperpolarization is effective in overcoming this ‘sodium inactivation’ in the depressed fiber so that the membrane potential approaches a normal sodium equilibrium potential at peak of activity.
Effects on homeostasis of 5-hydroxytryptamine, lysergic acid diethylamide and 2-brom-d-lysergic acid
Authors: McNeill J. Paul , Hampton John K.
Published: December 2017

Rats were injected intramuscularly with 5-HT or LSD and intravenously with 5-HT, LSD, BOL or equimolar concentrations of 5-HT + LSD or 5-HT + BOL. Appropriate saline controls were included. They were then exposed to a standard amount of Noble-Collip trauma. Animals receiving 5-HT i.m. showed a significant multiphasic mortality curve after trauma depending on dose of drug. With small doses, mortality significantly exceeded controls, but fell to a value near controls as dose increased until a critical level was reached at which point mortality again rose considerably above controls. When rats received 5-HT, LSD or BOL intravenously in the doses used, no significant differences from control were seen following trauma. Thus, a difference in mortality from trauma is seen based on route of administration of 5-HT and LSD. When an equimolar combination of 5-HT + LSD was given i.v., a significant increase in mortality following trauma over rats receiving either 5-HT + BOL or saline was noted.
Exchangeability of tissue potassium in skeletal muscle
Authors: Renkin Eugene M.
Published: December 2017

The quantity of "rapidly exchanging" K+ in isolated, skeletal muscles of dogs was determined by measuring the back-diffusion of K42 during perfusion with blood containing this isotopic tracer. This quantity was not constant, but varied from 18% to 88% of the total tissue K+. The rapidly exchanging fraction increased as arterial pressure and blood flow increased, and was greater in preparations with low vascular tone. It is concluded that the rapidly exchanging K+ represents all tissue K+ in well circulated regions, and the remaining K+ (slowly exchangeable) all tissue K+ in poorly circulated regions. As arterial pressure increases, or vascular tone decreases, the well circulated regions are increased at the expense of the poorly circulated regions due to opening or widening of minute vessels which were originally closed or narrowed.
Evaluation of sex and segment differences in spontaneous avian aortic arteriosclerosis
Authors: Weiss Harold S. , Fisher Hans
Published: December 2017

Thoracic and abdominal arteriosclerosis was measured in 42-month-old males, females, capons and poulards which had been maintained on a non-atherogenic' diet. Visually scored severity of lesions among segments and sexes was compared to severity estimated from aortic cholesterol and hydroxyproline concentrations and from blood pressure and plasma cholesterol levels. Aortic cholesterol was highly correlated with plasma cholesterol level, and aortic hydroxyproline with blood pressure. Better relationship to visual scores resulted from either a combination of the two aortic measurements or from the two blood measurements than from any single factor. However, thoracic aorta cholesterol had to be given more weight than thoracic hydroxyproline concentration in evaluating thoracic severity and conversely, abdominal hydroxyproline given more weight than abdominal cholesterol concentration in evaluating abdominal lesions. Similarly, plasma cholesterol had to be given more weight than blood pressure in evaluating thoracic severity and blood pressure more weight than plasma cholesterol in evaluating abdominal lesions.
Innervation of the vessels of the marrow cavity of certain bones
Authors: Weiss Ronald A. , Root Walter S.
Published: December 2017

The vasoconstrictor fibers passing to the marrow cavities of certain bones have been traced by cutting specific nerves and stimulating their peripheral ends. A reduction in marrow pressure signifies vasoconstriction. The tibia is supplied with vasoconstrictor fibers arising from the lumbar spinal cord and running mainly in the sciatic and tibial nerves. Vasoconstrictor fibers emerging from the lumbar region reach the femur by way of the femoral nerve and its branches. The humerus receives vasoconstrictor fibers from the upper thoracic segments. These are carried mainly in the median nerve. Vasoconstrictor fibers arising from T2, synapse in two-thirds of the cats in the stellate ganglion, pass up the cervical sympathetic chain and along the external carotid artery and its branches to reach the mandible. In one-third of the animals studied the synapses are located in the superior cervical ganglion.
Sex difference in histamine metabolism in rats
Authors: Kim K. S.
Published: December 2017

The pattern of endogenous histamine excretion in the urine of male and female rats has been studied. The major sex difference is that females put out approximately 25 times more free histamine than males. This difference in free histamine output accounts for the difference in total output. Castration increased free histamine output in males, but ovariectomy or combined ovariectomy and hysterectomy have no effect on output in females. The castration effect appears in 2–5 weeks. One milligram of testosterone propionate when injected subcutaneously suppresses the output of free histamine in castrated rats, but not in normal female rats. There are also sex differences in the handling of exogenous histamine. Castrated and female rats excrete a larger proportion of exogenous histamine in the free form. This indicates that a difference in handling rather than in rate of production may account wholly or partly for the observed sex difference in endogenous histamine output.
Seminal vesicle response to androgen with adrenaline, noradrenaline and acetylcholine
Authors: Grunt Jerome A. , Higgins James T.
Published: December 2017

In a study of the end-organ response to androgen, use has been made of the seminal vesicle of the rat. Observations were made of the in vitro spontaneous contractions and responses to autonomic stimulating drugs. Vesicles of castrated rats contract spontaneously in vitro. Testosterone propionate given to the rat before sacrifice inhibits contractions, as does injection of water-soluble androgen into the in vitro chamber. Vesicles of castrates have lower thresholds to adrenaline and possibly to acetylcholine, but not to noradrenaline. The thresholds to acetylcholine but not to noradrenaline are elevated after injection of water-soluble androgen into the in vitro chamber. Several interpretations are discussed. Androgen and the autonomic nervous system probably interact at or near the cell membrane of the vesicle musculature. The three drugs tested most likely act at different loci along the nerve—motor end plate—muscle system, and noradrenaline is probably not a primary mediating agent of spontaneous contractions of the vesicle of the castrated rat.
Effect of histamine on small and large vessel pressures in the dog foreleg
Authors: Haddy Francis J.
Published: December 2017

In order to determine how histamine raises small venous pressure in the dog foreleg, response of pressure during spontaneous blood flow was compared with that during constan blood flow. With spontaneous blood flow, small venous pressure rose in response to both slow and fast rates of infusion of histamine into the brachial artery. Rise of small venous pressure preceded rise of interstitial pressure. Edema appeared whenever small venous pressure exceeded 26 mm Hg for 7 minutes or more. With blood flow held constant, slow rates of infusion failed to either raise small venous pressure or produce edema. Pressure rose and edema appeared despite a constant blood flow rate when the rate of infusion was increased to values which lowered systemic arterial pressure. Pressure increase was unaffected by section of foreleg nerves but was partially abolished by adrenergic blockade. Rapid intravenous infusion during constant blood flow raised small venous pressure much less and this rise was completely abolished by adrenergic blockade. These studies indicate that low rates of infusion into the brachial artery raise small venous pressure by arteriolar dilatation whereas high rates raise this pressure both by arteriolar dilatation and venous constriction. Venous constriction probably results both from a direct action of histamine and indirectly through an adrenal discharge. The study also suggests that elevation of capillary hydrostatic pressure is an adequate explanation for histamine edema.
Effect of diabetes on cholesterol and fatty acid synthesis in the rat aorta
Authors: Foster Daniel W. , Siperstein Marvin D.
Published: December 2017

The synthesis of cholesterol and fatty acids from acetate-1-C14 was studied in the aortas and livers of 42 diabetic rats and their normal controls. Hepatic cholesterol synthesis was significantly increased in 13, decreased in 13, and unchanged in 16 of the 42 animals. Fatty acid synthesis was depressed in the liver in 39 of the 42 diabetic rats. Aortic cholesterogenesis was increased in only 2 of the 13 aortas from the same rats showing elevated hepatic cholesterol synthesis. Fatty acid synthesis was depressed in 21 of 42 aortas from the diabetic group. It is concluded, therefore, that the aorta is relatively resistant to stimulation of cholesterol synthesis by diabetes even when hepatic cholesterol synthesis in the same animal is elevated. Lipogenesis on the other hand is commonly depressed in the aorta as well as the liver. Cholesterol was purified through dibrominization and both normal and diabetic aortas were shown to be capable of carrying cholesterol synthesis to completion.
Relation of glutaminase I activity to glutamic acid concentration in the rat kidney
Authors: Goldstein Leon , Copenhaver J. H.
Published: December 2017

Injection of sodium glutamate had no significant effect on renal glutaminase I activity in untreated rats but suppressed the rise in enzyme activity which follows repeated ammonium chloride administration. Injection of glutamine produced a small rise in enzyme activity in untreated rats but suppressed the enzyme response in ammonium chloride-treated animals. Injection of glycine had no significant effect on enzyme activity in treated or untreated rats. A significant fall in renal glutamic acid concentration was observed 2 hours after the administration of ammonium chloride. These results suggest that there is a relation between the concentration of glutamic acid and the synthesis of glutaminase I in the kidney of the rat.
Active transport of calcium by the small intestine of the rat
Authors: Schachter David , Dowdle Eugene B. , Schenker Harris
Published: December 2017

The rates of active transport of calcium in vitro by everted gut-sacs prepared from the proximal small intestine of the rat have been quantified and expressed in absolute units. A maximal rate of transport has been measured. The bulk of the calcium transferred to the serosal surface of the gut-sac is ionized calcium, suggesting that the process is an active cation transport mechanism. The active transfer is relatively specific for Ca++, and no significant accumulation of Mg++, Sr++, Ba++ or K+ in the fluid bathing the serosal surface could be demonstrated. The active transport of calcium in vitro is greater with gut-sacs from growing than from older rats, and it is greater with gut-sacs from pregnant than from nonpregnant rats. The results suggest that the active transport mechanism can increase the intestinal absorption of calcium facultatively to meet the needs of the organism.
Time-order of ventricular activation for premature beats in sheep and dogs
Authors: Hamlin Robert L. , Smith C. Roger , Redding Richard W.
Published: December 2017

Average durations for the sinus QRS complex were 0.035 seconds for the sheep and 0.041 seconds for the dog. The average prolongation of premature beats was 145% in the sheep and 210% in the dog. Spatially, the mean QRS vector for both species was directed coplaner to the median sagittal plane—the sheep being minus 120 degrees at a magnitude of 0.8 mv, and the dog being at 88 degrees and a magnitude of 1.4 mv. In both species, premature beats from left ventricular focuses were directed cephalically; and from right ventricular focuses, caudally. It is difficult to explain why premature beats from identical focuses in sheep and dog hearts have nearly identical mean spatial QRS vectors, yet the prolongation and magnitude is so much greater in the dog whose heart is less than one-half the size of the sheep's. Of the possible explanations for the data: ( a) that the activation for premature beats is all muscle fiber to muscle fiber; ( b) that the impulse quickly re-enters into the Purkinje system; or ( c) that a combination of the two exists, the last is most tenable based upon anatomic studies describing the more complete penetration of the Purkinje fibers into the epicardium of sheep.
Mechanism of acute erythrocyte loss following burn
Authors: Gilmore J. P. , Fozzard H. A.
Published: December 2017

Direct measurements of red cell mass, osmotic fragility change and plasma hemoglobin immediately following a 22 cal/cm2 30% surface area burn in the dog indicate that a 13% decrease in red cell mass occurs, at least half of which can be attributed to the direct destruction and changes in osmotic fragility of erythrocytes. It was also observed that the red cell mass may increase following burn as a result of splenic extrusion of sequestered erythrocytes. The results of these experiments indicate that while there is some physiologic basis for whole blood therapy following burn, the more immediate requirement is the replacement of fluid.
Relaxation after extreme contraction, studied with isotonic technique
Authors: Norris Forbes H.
Published: December 2017

Posttetanic relaxation was studied under nearly isotonic conditions, using an electromagnetic muscle lever and frog gastrocnemius. Greatly prolonged relaxation occurred when, during contraction, the muscle was thrown into slack, reaching lengths less than the minimum length in situ but greater than 40% of initial length. Contraction under such conditions has been called extreme contraction. The relaxing muscle afterward resisted stretching with tensions estimated to average 42% of twitch tension, and a shift in a length-tension characteristic seemed to have taken place. However, adequate stretching or loading overcame this resistance, and appeared to result in complete reversibility. The similarity of relaxation curves after normal and extreme contractions was demonstrated objectively by fitting the curves with the same mathematical relationship between length and time. Possible mechanisms accounting for extreme contraction are discussed.
Evoked slow and unit responses of the cerebral cortex following repetitive stimulation
Authors: Boyarsky L. L. , Sant'Ambrogio G. , Frazier D.
Published: December 2017

Unit and slow primary responses have been compared in the sensorimotor cortex of the cat to stimulation of the radial nerve. As frequency of stimulation is increased, the amplitude of the primary decreases but remains constant at a given frequency. The evoked positive and negative phases of the primary usually disappear at frequencies below 30/sec. Unit responses, however, can still be found in a region where the primary is absent. As frequency of stimulation is raised, the unit responses begin to fail intermittently with complete disappearance of the spikes at about 60/sec. but firing can be encountered at much higher frequencies. In some preparations intermittent unit firing occurs at rates of stimulation between 500 and 1000/sec. The relationship of these findings to cortical mapping is discussed. It is concluded that these data do not support the method of mapping which depends upon the use of the evoked slow potentials.
Localization of urine acidification in the mammalian kidney
Authors: Gottschalk Carl W. , Lassiter William E. , Mylle Margaret
Published: December 2017

Fluid was collected by micropuncture from individual renal tubules of anesthetized rats and its pH determined with the quinhydrone microelectrode. The single glomerular sample and early proximal fluid were isohydric with arterial blood, but later proximal fluid usually showed progressive acidification. The maximum proximal fall in pH was 0.43 u in nondiuretic rats, 0.56 u during profuse glucose or mannitol diuresis, and 0.78 u in rats previously loaded with ammonium chloride and undergoing glucose diuresis. Fluid from the early distal convolution was usually acidified relative to arterial blood but was not significantly different from late proximal fluid. Progressive acidification probably also occurred in the distal convolution. The pH decreased further in the collecting ducts, much more so in the nondiuretic state than during diuresis. The quantitative importance of proximal reabsorption of HCO3– and, by inference, H+ secretion is emphasized. It is suggested that the pH of tubular fluid may increase in the thin descending limb of the loop of Henle, especially in a kidney elaborating a concentrated urine, because of increased concentration of HCO3–.
Factors affecting gastric secretion in thoracic-duct lymph of dogs
Authors: Johnston Ivan D. A. , Code Charles F.
Published: December 2017

Thoracic-duct lymph was collected from dogs during various phases of gastric secretion. The lymph samples were injected intravenously into dogs with vagally innervated and denervated pouches while these were secreting at slow rates in response to the continuous intravenous injection of small quantities of histamine. About half the samples inhibited gastric secretion. The rest produced transient stimulation or had no effect. The greatest degree of inhibition occurred when lymph collected immediately after a meal was injected. When fatty lymph was separated into fat and nonfat fractions, the fat-containing portion of lymph stimulated gastric secretion slightly, while the nonfat fraction carried the inhibitory influence when it was present. Systemic reactions were noted in one-third of the animals that had an inhibitory response. The occurrence of stimulatory or inhibitory factors in the lymph did not appear to be related to particular phases of gastric secretion.
Species differences in altitude tolerance following X-irradiation
Authors: Newsom Bernard D. , Kimeldorf Donald J.
Published: December 2017

The relationship between altitude tolerance and food consumption was investigated in irradiated and nonirradiated animals of several species. Food consumption was measured for 3 days following a mid-lethal dose of x-irradiation to assess the degree of postirradiation anorexia. Seventy-two hours after irradiation those animals, as well as ad libitum-fed and food-deprived nonirradiated animals were exposed to a simulated altitude tolerance test. The mortality produced in 4 hours was used as the criterion of hypoxic tolerance for each species. Irradiated rabbits and rats exhibited a severe decrease in food consumption and an increased hypoxic tolerance. Food consumption of mice was depressed during the 3 days following irradiation although the effect was much less than that observed for rats and rabbits. Guinea pigs and hamsters exhibited only a slight decrease in food consumption with recovery occurring after 24 hours. Mice, guinea pigs and hamsters did not exhibit a significant increase in hypoxic tolerance 3 days after radiation exposure. When nonirradiated rabbits, rats, mice and guinea pigs were food deprived, the hypoxic tolerance was significantly increased in all species.
Carbohydrate metabolism in rats with chronic uremia
Authors: Boucot Nancy G. , Nurser Elizabeth K. , Merrill John P.
Published: December 2017

In order to evaluate the effects of the chronic uremic syndrome upon some aspects of carbohydrate metabolism in vivo, determinations of gastric and intestinal glucose absorption, and of hepatic glycogen deposition were made in 39 chronically uremic rats and in 49 litter-mate controls. A surgical method for producing chronic uremia was developed. Rats fasted for 24 hours were given a glucose gavage of standard concentration. Three hours later residual gastric and intestinal glucose content and liver glycogen content were determined. No statistically significant difference between the two groups was found in either glucose absorption from the gastrointestinal tract or in glycogen deposition.
Excretion of l-malic acid in the chicken
Authors: Vishwakarma P. , Lotspeich W. D.
Published: December 2017

The mechanism of excretion of malic acid has been studied during infusion of sodium salts of l-malic acid, succinic acid and malonic acid in the chicken. Infusion of preformed l-malate results in its filtration and reabsorption in the nephron; no renal tubular secretion is seen under these circumstances. However, when succinate is infused in the renal portal circulation, malate is excreted in larger amounts on the ipsilateral side than on the other. Malonate, a succinoxidase inhibitor, not only fails to abolish this excretion but actually enhances it. Infusion of malonate alone does not produce any excretion of malic acid. It is concluded that the renal tubular secretion of l-malate is limited to that which is synthesized in the tubular cells and does not occur even when large amounts of infused l-malate are present in the peritubular circulation. The enhancement of malate excretion by malonate during succinate infusion may occur from either malonate decarboxylation or malonate suppression of a malate reabsorptive limb in the nephron.
Effect of small electric currents on intravascular thrombosis in the visualized rat mesentery
Authors: Sawyer P. N. , Suckling E. E. , Wesolowski S. A.
Published: December 2017

An experiment was designed to determine the effect of small electric currents on the blood vessels of the rat mesoappendix and mesentery, bathed with 1% gelatin Ringer's solution at temperature of 37° and pH 7.4. Current electrodes were applied to either edge of the rat mesoappendix. A potentiometric circuit was used to determine equipotential lines and transvascular potential differences. A dissecting microscope at 160x magnification was used to observe the rat mesoappendix. An electric field was created by the current passed. Total currents as small as 20 µa with a pole-to-pole potential difference of 20–30 mv maximum and a transvascular potential drop of 1–3 mv often resulted in intravascular occlusion of the vessels in the rat mesoappendix. The effective electric currents and their density were within the range of intensity attained by biologic injury currents. The possibility that injury currents in injured biologic tissues may be related to intravascular occlusion is discussed.
Effect of fluoroacetate on the metabolism of isotopic acetate and lactate by the isolated perfused dog gastrocnemius
Authors: Lifson Nathan
Published: December 2017

A study was made of the metabolism of C13-labeled acetate and lactate by the repetitively contracting (2/sec.), isolated, perfused dog gastrocnemius which had been poisoned by sodium fluoroacetate. When the fluoroacetate was administered at least 1/2 hour before the substrates, there followed a weakening of the contractions, a decrease in total CO2 output, an enhanced disappearance of glycogen, an accumulation of lactic acid and a decrease in the pH of the blood. Under these conditions it was also found that the fluoroacetate greatly reduced the conversion to CO2 of the carboxyl carbon of acetate and of the noncarboxyl carbons of lactate, but the carboxyl carbon of lactate still contributed a large fraction of the CO2. These isotopic results are qualitatively consistent with predictions made from current concepts of intermediary metabolism and mode of action of fluoroacetate.
Steroid excretion by guinea pigs exposed to cold for prolonged periods
Authors: Sobel Harry , Sideman Martin , Arce Rodrigo
Published: December 2017

Guinea pigs were exposed to cold at a temperature of 2°–4°C for a period of 92 days. With daily cabbage supplementation mortality was low although growth rate was impaired. Urinary corticoid excretion increased markedly being more than doubled initially and averaged approximately 1.8 times that of unexposed control animals. Ketosteroid excretion increased moderately initially but values did not differ appreciably for unexposed controls in subsequent periods. The ratio ketosteroids/corticoids remained remarkably constant throughout the period of exposure. Statistically significant negative correlations were observed between the increment in weight and increment in creatinine excretion with the average corticoid excretion values over a 2-month period whether the animals were maintained at room temperature or in the cold. Similar positive correlations were observed with the ratio ketosteroids/corticoids. Following return to room temperature steroid excretion values fell abruptly although the adrenals were markedly hypertrophic. The animals which had been cold exposed exhibited greater corticoid excretion values after a standard dose of ACTH than did unexposed controls.
Simultaneous determinations of blood pressure and blood pH in cases of suspected pheochromocytoma
Authors: Roth Grace M. , Roedling Herbert A. , Gifford Ray W.
Published: December 2017

Eight hundred fifty-seven determinations of the pH of venous blood with simultaneous blood pressure observations were carried out on 590 patients. The pH of venous blood of the patients who had been under medication for a long period before the tests did not vary significantly from that of patients who had had no medication. The most consistent result was the rise in the pH of venous blood 30 minutes after a dose of phentolamine hydrochloride (Regitine). The oral administration of 40 grains of sodium bicarbonate did not increase the response of the blood pressure during the histamine test, irrespective of the type of previous medication, even though the pH of the venous blood was low initially and rose to normal levels after the administration of the sodium bicarbonate. This may be due to the fact that none of the patients had pheochromocytomas with excessive release of pressor amines.
Metabolism of creatine-1-C14 by vitamin E-deficient and hyperthyroid rats
Authors: Fitch Coy D. , Coker Randle , Dinning James S.
Published: December 2017

Normal, vitamin E-deficient and hyperthyroid rats were given creatine-1-C14 intraperitoneally, and its incorporation into skeletal muscle was determined. The incorporation of the creatine into skeletal muscle was increased in vitamin E-deficient rats while serum creatine-C14 activity was reduced. Hyperthyroidism led to a decreased incorporation of creatine into skeletal muscle and to elevated serum creatine-C14 levels. It is concluded that in vitamin E deficiency there is an inability of skeletal muscle to retain creatine and that in hyperthyroidism there is a block in the entry of creatine into skeletal muscle.
Recovery cycle of visual cortex of the awake and sleeping cat
Authors: Evarts Edward V. , Fleming T. Corwin , Huttenlocher Peter R.
Published: December 2017

Cats with chronically implanted electrodes were employed in studies of the effects of sleep and waking on the recovery cycle of the cortical response to electrical stimulation of lateral geniculate radiations. Identical test and conditioning stimuli were delivered to the geniculate radiations at intervals of 3.2–1000 msec. At intervals between 16 and 200 msec., the subnormality of the test response was more marked during waking than during sleep. Amplitude of responses to single stimuli was greater during sleep than during waking. The results are discussed in relation to the hypothesis that there is an increase in the activity of inhibitory processes in the visual cortex during waking.
Coagulation properties of canine thoracic-duct lymph
Authors: Langdell R. D. , Bowersox L. W. , Weaver R. A. , Gibson W. S.
Published: December 2017

Coagulation studies were made on thoracic-duct lymph obtained from semifasting healthy adult dogs. Prothrombin, fibrinogen, antihemophilic factor (AHF) and plasma thromboplastin component (PTC) were found to be present in lymph in concentration of about 30–60% of plasma levels. One-stage type clotting tests using either complete or partial thromboplastins give variable results. Some samples of lymph are as active in these tests as is plasma while some are considerably less active. The lymph samples are not fully active at the time of collection. On exposure to glass surfaces in the presence of anticoagulant, the clotting time becomes shorter during the first 20–40 minutes. Coagulating lymph has a high residual prothrombin even after 18–24 hours in glass containers. Thoracic-duct lymph contains sufficient thromboplastic materials so that adequate amounts of thrombin can form to produce a fibrin clot, but it does not contain the thromboplastic materials required for complete prothrombin utilization. The study of lymph coagulation appears to be an important aspect of the general process of coagulation since thrombocytes appear to play a minor role in its coagulation properties.
Ca exchange in isolated turtle ventricle
Authors: Henrotte J. G. , Cosmos E. , Fenn W. O.
Published: December 2017

Ca content and Ca exchange (studied by means of the isotope Ca45) have been determined in vitro in turtle ventricles and frog skeletal muscles. The Ca exchangeability has been found much greater in cardiac than in skeletal muscles. Stretching further increases the cardiac Ca exchange and the hypodynamic state decreases it. Stimulation at a maximal rate of 24/min. has little effect in out experimental conditions and changes in total Ca content are small. It is suggested that the greater exchangeability of the Ca of cardiac as compared to skeletal muscle may explain the fact that cardiac is more sensitive than skeletal muscle to changes in the Ca concentration of the medium.
Induced alterations in metabolism of dl-norleucine-2-C14 in the intact cow
Authors: Kaneko J. J. , Black A. L. , Kleiber Max
Published: December 2017

The metabolism of dl-norleucine-2-C14 was compared in intact cows before and after prolonged injections of unlabeled norleucine. The appearance of C14 in respired CO2, milk, and urinary acetone indicated that the cow readily metabolizes norleucine. The distribution of C14 in the urinary acetone was found to be compatible with a pathway involving deamination, decarboxylation and subsequent ß-oxidation. Injections of unlabeled norleucine resulted in accumulation of a pool of unlabeled norleucine in the cow's tissues. Relative increases were noted in the specific activities of the respired CO2 and in milk constituents, and absolute decreases were noted in the specific activities of urinary acetone—nearly to zero. These findings suggest that oxidative and synthetic mechanisms had been stimulated by the prolonged injections of unlabeled norleucine.
Distribution of water between intracellular and extracellular phases in incubated tissue slices
Authors: Swan A. G. , Ellington E. E. , Miller A. T.
Published: December 2017

Guinea pig liver and kidney cortex slices swelled when incubated under a variety of abnormal metabolic and osmotic conditions. Simultaneous measurement of the inulin space permitted the calculation of the distribution of the water of swelling between the intracellular and extracellular compartments. Swelling was entirely intracellular in the kidney cortex slices, while both intracellular and extracellular compartments were involved in the swelling of liver slices. Under all the conditions studied, kidney slices had a greater capacity for resisting changes in the volume and distribution of tissue water than did the liver slices.
Reciprocal changes in feeding behavior produced by intrahypothalamic chemical injections
Authors: Epstein Alan N.
Published: December 2017

Feeding behavior was studied in rats bearing chronic intrahypothalamic cannulas through which small quantities of chemical substances could be injected from remote microsyringes. Procaine-HCl injected bilaterally into the ventromedial hypothalamic regions in a dose range of 0.5–6.0 µl elicited normal feeding behavior repeatedly in satiated animals. Hypertonic saline injections into the medial hypothalamus suppressed spontaneous eating in hungry animals. Conversely, injections of hypertonic saline into the lateral hypothalamus elicited eating, and eating was suppressed by procaine injections into this same area. Drinking was elicited in a single animal bearing bilateral lateral cannulas. Control injections of isotonic saline did not regularly produce any of these effects. Dextrose injected bilaterally into the ventromedial hypothalamus did not suppress spontaneous eating in food-deprived rats. These results offer additional evidence for the concept that there exists in the hypothalamus a dual mechanism involving a medial inhibitory system of neurons and a lateral excitatory system of neurons functioning reciprocally in the control of food intake.
Alterations in the stability of mammalian A fibers produced by N2O and by CO2
Authors: Carpenter F. G.
Published: December 2017

In an oxygen atmosphere, freshly excised r ammalian nerves exhibit a spontaneous repetitive discharge amounting to some 100 µv throughout the range 20°–35°C. This instability may be attributed to lack of CO2 in experimental environment, since it disappeared after 5% of an atmosphere of this gas was introduced. Discharge was abolished in an identical manner if nerves were soaked for 2 hours in a nonbicarbonate buffered Ringer's solution (10 mm/l. of trishydroxymethyl-aminomethane). If under these conditions the preparation was exposed to 2–4 atm. of N2O the instability reappeared manifested as a repetitive discharge which might exceed 200 µv. This activity arises from large diameter ‘A’ fibers, since the smaller fibers in the population are inexcitable in pressure range where instability is most prominent. In the same pressure range postspike oscillations appeared when the nerves were stimulated electrically with a maximal shock. Production of spontaneous rhythmicity and postspike oscillations by specific amounts of N2O are believed to result from the same alteration of the neuronal membrane. Thus an increase in permeability of this structure to K may account for these findings. Mechanism of the alteration by N2O might be found in a failure of Ca to exert its stabilizing action.
Autonomic and EEG responses to cerebellar stimulation in rabbits
Authors: Sawyer Charles H. , Hilliard J. , Ban T.
Published: December 2017

The vermis of the cerebellum in 27 rabbits anesthetized topically with procaine and immobilized with Flaxedil was explored stereotaxically and stimulated (0.5-msec. square waves, 300 cps., 5-sec. bursts) at various voltages. Autonomic effects were recorded as were also EEG changes in frontal and limbic cortex, thalamus, hypothalamus and amygdala. Stimulation of the anterior lobe characteristically induced an arterial pressor effect associated with mydriasis-exophthalmos and an aroused EEG. Responses from stimulating the posterior lobe were more variable. Sympathetic effects and an aroused EEG were often accompanied by a depressor response during stimulation followed by a pressor ‘rebound’ at the end of stimulation. In several rabbits, stimulation of the pyramis or uvula evoked a sleeplike EEG with spindles in the frontal cortical record, accompanied by parasympathetic miosis-enophthalmos during stimulation, with a reversal to arousal and sympathetic phenomena immediately afterward. These effects were eliminated by coagulation of the diencephalon at a time when pressor responses, reflexly to pain or directly to stimulation of the lower brainstem, were unimpaired.
Effect of increased portal pressure on sorption of water and sodium from the ileum of dogs
Authors: Shields Robert , Code Charles F.
Published: December 2017

The effect of increased portal pressure on the ileal sorption of sodium and water was determined in acute studies on anesthetized dogs. Portal pressure was controlled by an inflatable cuff placed around the vein and the movement of sodium and water into and out of a segment of the ileum was determined by use of Na22 and D2O. With the cuff in place but not inflated, exsorption of sodium (movement from blood to intestine) increased, but insorption of sodium (movement from intestine to blood) decreased, and the movement of water was little affected. Further increases in portal pressure produced a progressive increase in the rate of exsorption of sodium without having further significant effects on the insorption of sodium or the movement of water.
Effect of podophyllin lignans on mast cell morphology in rat peritoneal fluid
Authors: Padawer Jacques
Published: December 2017

The morphology of mast cells is affected by podophyllotoxin and related substances. Other nondividing cells respond similarly. The changes observed are cytoplasmic and identical to those demonstrated following treatment with colchicine. Biological activity of podophyllin lignans is referable to specific molecular configuration and, in the mast cell system, parallels their activity in other assays such as tumor damage and mitotic inhibition of regenerating liver. These findings extend those demonstrated for a series of colchicine derivatives and, in this respect, emphasize the similarities in biological activity of the two compounds. They also underline further the unlikelihood that well-differentiated mast cells normally undergo mitosis. Because mast cells respond rapidly and sensitively to these specific drugs, it is suggested they afford a useful index of probable carcinostatic activity. Thus, colchicine or podophyllotoxin congeners could be prescreened readily, using few animals and small amounts of material.
Endogenous excretion and intestinal capacity for absorption of cholesterol in the dog
Authors: Wojciech R. , Janecek H. M. , Ivy A. C.
Published: December 2017

Using five dogs weighing an average of 13.9 kg and fed a sterol, fat free diet, it was found that the fecal excretion of digitonin-precipitable sterol amounted to an average of 138 mg/day. The addition of oleic acid (6% by weight) to the diet did not significantly change the endogenous excretion. The average intestinal capacity to absorb exogenous cholesterol of the group of dogs, ranging in weight from 10.7 to 18 kg, was 1.05 g of cholesterol per day. When cholesterol-4-C14 was given orally as one dose under the above dietary conditions and the feces collected for 8 days and fractionated, and the radioactivity of each fraction determined, it was found that the non-95% ethanol residue contained only a trace, the unsaponifiable material (UM) 29%, the saponifiable material (SM) 17.7% of the C14 administered. Of the radioactivity in the UM, 80% was digitonin precipitable. In 8 days 46.7% of the administered C14 was recovered. These results are similar to those obtained on the rat.
Cholinergic stimulation and blockade on urinary bladder
Authors: Gyermek Laszlo
Published: December 2017

The relative potency and mode of action of some cholinomimetics were investigated on the pelvic nerve-bladder preparation of the dog and cat. Most of the cholinomimetic agents used proved to be considerably more potent than acetylcholine (ACh). The peak activity was shown by muscarine and dl-muscarone, which were 100–300 times more potent than ACh. Atropine did not markedly influence the effect of the electrical stimulation on the pelvic nerve. Atropine also proved to be ineffective against the actions of 1,1-dimethyl,4-phenyl piperazinium iodide, serotonin, histamine, and BaCl2. It antagonized the effects of ACh only moderately, but completely inhibited the effects of muscarine and methacholine. After atropinization, hexamethonium inhibited the effects of nerve stimulation and ACh. ACh has a significant ganglionic component of its action on the bladder. It is postulated that part of the parasympathetic effector sites of the bladder functionally resemble autonomic ganglions. These ganglionic type of receptors seem to play an important role in the effects of parasympathetic nerve stimulation and in the action of ACh.
Thiocyanate space of rat brain
Authors: Streicher Eugene
Published: December 2017

The thiocyanate space of rat brain was found to be a function of the plasma level of the ion, although, after several doses of 1–5 mm/kg sodium thiocyanate, a dynamic equilibrium was readily established and maintained between brain and plasma. Although potentially distensible, a figure of 5%, or less, is suggested for the normal volume of the extracellular compartment of rat brain.
Renal sodium transport and oxygen consumption
Authors: Kiil Fredrik , Aukland Knut , Refsum Harald E.
Published: December 2017

Glomerular filtration rate and renal blood flow were increased in dogs by infusion of 2% glycine and hypertonic NaCl at rates of 8 ml/min. This procedure resulted both in an increased rate of sodium reabsorption and in increased oxygen consumption. Approximately six equivalents of sodium were transported per equivalent oxygen consumed, a ratio similar to that obtained by others when glomerular filtration rate had been reduced. These observations strongly suggest that a large part of renal oxygen consumption is related to the transport of sodium. When the rate of sodium reabsorption was reduced during mannitol diuresis, arteriovenous oxygen difference decreased, but renal oxygen consumption remained unchanged. It is suggested that the active sodium transport in the proximal tubules continues at an unchanged rate during mannitol diuresis but that net reabsorption is reduced owing to increased passive influx into the tubular lumen when the transtubular concentration gradient increases. Other interpretations are discussed.
Uterine peptidase activity in the rat and rabbit during pseudopregnancy
Authors: Albers H. J. , Bedford J. M. , Chang M. C.
Published: December 2017

Uterine peptidase levels in the rat and rabbit were determined during the estrous cycle and pseudopregnancy. During the estrous cycle higher peptidase activity was found in rat uterine homogenate and uterine fluid at the proestrous and estrous stages. Highest peptidase levels were found in rat uterine homogenate and in rabbit endometrium during pseudopregnancy, a peak being reached at the stage of implantation. The peptidase activity of rabbit fallopian tube homogenate was essentially constant during pseudopregnancy. These findings indicate that uterine peptidase activity changes in response to change in estrogen and progesterone levels. No such change is shown by the fallopian tube peptidases. Maximal activity at implantation may reflect preparative changes of the uterus for reception and implantation blastocysts.
Stop flow analysis of renal function in the monkey
Authors: Vander Arthur J. , Cafruny Edward J.
Published: December 2017

Stop flow analysis has been used to study renal function in the macaque monkey. Mannitol diuresis produced excretion of 58–70% of filtered water and 22–34% of filtered sodium. An absence of water and sodium reabsorption from the proximal tubule during ureteral occlusion was observed in three of four experiments, suggesting that this portion of the monkey nephron cannot transport sodium as efficiently as the canine proximal tubule during osmotic diuresis or that it is less permeable to water. Creatinine secretion was observed and localized to the same portion of the proximal tubule which secretes PAH. Inorganic phosphate and glucose reabsorption also occurred in the proximal tubule. Sodium, chloride, and potassium stop flow patterns were identical to those reported for the dog. Chlorothiazide caused an inhibition of distal tubular sodium reabsorption and an enhancement of potassium secretion in the distal nephron. Proximal tubular activity of the drug could not be evaluated.
Renal distribution of sodium in potassium-depleted and vitamin D-intoxicated rats
Authors: Eigler Jochen O. C. , Salassa Robert M. , Bahn Robert C. , Owen Charles A.
Published: December 2017

The concentration and distribution of sodium and potassium in small consecutive portions of kidneys of potassium-depleted and vitamin D-intoxicated hydropenic rats were estimated by a procedure based on the principle of specific activity. By this method sodium and potassium could be measured in bits of tissue weighing less than 2 mg. The results were correlated with the corresponding urinary osmolality. In both experimental groups, a marked impairment of the elaboration of osmotically concentrated urine was observed. The relative distribution of sodium and potassium in the kidney was not altered significantly. Associated with the decreased osmolality of the urine, however, was an approximately proportionate or slightly greater reduction in the content of sodium in the papilla. The findings suggest that a failure to establish maximal medullary hypertonicity, as indicated by the diminished accumulation of sodium, may be an important factor in the impairment of concentrating mechanisms.
Diurnal activity rhythm of rats with lesions of superior colliculus and visual cortex
Authors: Altman Joseph
Published: December 2017

The role of two central nervous visual structures. the superior colliculus and striate cortex, was investigated in the coordination of the day-night activity cycles of rats. While both normal rats and rats with bilateral lesions in superior colliculus or striate cortex showed higher rates of general activity at night than during the day, the brain-operated animals showed less difference than the normals. Decrease in nocturnal activity preference was considerable in the striate cortex lesion group in which mean destruction of tissue was as high as 91%, whereas in the superior colliculus similar effects were obtained with mean destruction of only 41% of tissue.
Thermoregulatory responses of dogs after alteration of peripheral sensitivity
Authors: Helmendach R. H. , Meehan J. P.
Published: December 2017

Topically applied pharmacologic agents were used to alter skin sensitivity of unanesthetized dogs subjected to rapid changes in thermal state. The anesthetic pramoxine hydrochloride was utilized to depress peripheral sensitivity; menthol was used to enhance it. Application of these agents produced shifts in specific skin temperature at which activation and suppression of both panting and shivering occur. These changes were interpreted as indicating peripheral mediation in control of thermoregulatory end mechanisms. Both substances exhibited a greater effect on thermoregulatory responses to cooling than to heating. Consequently, one may infer that the peripheral cold-fiber effect exerts a greater influence on thermoregulatory end mechanisms than does the warm-fiber effect.