bluuebunny/crossref_metadata_2025 huggingface dataset:
Conditioning factors influencing evolution of experimental glomerulonephritis in rabbits
Authors: Teodoru Constantin V. , Saifer Abraham , Frankel Harry
Published: December 2017

Unilateral nephrectomy (UN) and/or oral saline administration in rabbits did not induce alterations in the concentration of various blood serum constituents for observation periods ranging from 1 to 6 months. Duck antirabbit-kidney immune serum (NTX) given i.v. to UN animals produced an acute glomerulonephritis significantly more severe than in parallel controls. All UN animals died from dry uremia within 3–4 weeks following serum administration. As compared to the other groups, the UN showed the highest retention of urea nitrogen, creatinine and uric acid. When injected into saline-drinking animals, NTX produced either subacute glomerulonephritis, anasarca, convulsions and death from wet uremia, or chronic glomerulonephritis with polyuria and hyposthenuria as the main clinical manifestations. As compared to the other groups, the saline-drinking animals showed lowest serum albumin and highest cholesterol levels. The serum albumin level appeared to be related to the urinary loss of albumin and not to the severity of the disease. The albumin concentration per unit volume was similar in the urine of various groups; hence the albumin loss depended upon the 24-hour urine output, i.e. highest in saline drinking, lowest in UN groups. Hypercholesterolemia and edema inversely paralleled the serum albumin level, being pronounced in saline-drinking and mild in UN animals.
Ketone body metabolism in ascorbic acid deficiency: in vivo utilization of ketone bodies in guinea pigs
Authors: Bacchus Habeeb , Debons Albert F. , Levin Sidney , Wallace John W.
Published: December 2017

Blood and urinary levels of ketone bodies were studied in normal, ascorbic acid-deficient, and pair-fed control, guinea pigs. The resting levels of ketone bodies in the blood and urine throughout the course of ascorbic acid-deficiency do not differ significantly from those of control animals. The ketonemic response to fasting is greater in the control animals than in the ascorbic acid-deficient animals. The disappearance of injected ketone bodies (ß-hydroxybutyrate) is decreased in the ascorbic acid-deficient animal. The data suggest that in ascorbic acid-deficiency there is a decreased utilization of ketone bodies coupled with a decreased spontaneous ketogenesis.
Immediate effects of stretch on muscle contractility
Authors: Alexander Robert S.
Published: December 2017

A study has been made of changes in the contractile response in striated muscle (isolated frog gastrocnemius) and smooth muscle (puppy bladder in situ) during the stress relaxation which follows sudden stretch. In both types of muscle, there is a progressive increase in the peak contractile response as partial decay of the stretched resting tension occurs. With large stretches of striated muscle and with any significant stretch of smooth muscle, this phenomenon is followed by a further decay in resting tension without alteration in the magnitude of the contractile response. Immediately after sudden stretch, there is a brief period during which the contractile response may be reduced. These results are interpreted in the light of theoretical muscle models, and it is emphasized that part of the stress relaxation process appears to involve the lengthening of shortened contractile links so that they become actively contractile.
Effect of vagotomy on secretin and pancreozymin activity of intestines of albino rats
Authors: Dorchester J. E. C.
Published: December 2017

Crude HCl extracts were made from the intestines of vagotomized albino rats and their paired fed controls. Using a simple cross-over design requiring two rabbits for each assay, the extracts were compared for secretin and pancreozymin activity. Significant differences in both the volume and amylase activity of the pancreatic juice secreted in response to 5-ml injections of the extracts were observed. It was concluded that vagotomy led to a reduction in the secretin activity, but an increase in the pancreozymin activity of the intestines.
Induction of estrus by electrical stimulation
Authors: Hays R. L. , Carlevaro C. H.
Published: December 2017

Using the apparatus designed for the electroejaculation of bulls, the reproductive organs of anestrous cows were electrically stimulated through the rectal wall. Forty-three per cent of the cows which had been in anestrus for 50 or more days after calving came in heat within 7 days after an electrical stimulation as compared to 13% of the controls. Fifty per cent of cows which had shown anestrus for 50 or more days after a normal heat period showed estrus in 7 days after stimulation as compared to 5% of the controls. Ovulation occurred at this estrus as determined by palpation and by conception after breeding. It is suggested that gonadotrophic hormones are released due to the stimulation of the reproductive organs.
Influence of variations in blood flow and of dinitrophenol on renal oxygen consumption
Authors: Levy Matthew N.
Published: December 2017

Implications of the cell-separation theory relative to renal oxygen consumption were tested to determine a) if the tubular cells are able to extract oxygen more efficiently at reduced flows if additional oxygen is made available in physically dissolved form; b) if the renal parenchymal cells are able to extract oxygen more efficiently under the influence of an effective metabolic stimulant. It was found that, even when an additional quantity of at least 1 vol. % of oxygen was furnished to the kidney in physically dissolved form, the extraction of oxygen still remained constant over a wide range of renal blood flows. Since this was not attended by any alteration in the intrarenal hematocrit ratio, this finding was contrary to predictions based upon the cell-separation theory. Intravenous 2,4-dinitrophenol was found to increase the renal oxygen extraction very significantly, without altering the intrarenal hematocrit ratio. This implies that the capillary blood perfusing the renal tubules must not be virtually completely desaturated at normal or even moderately reduced flows, and is not consonant with the implications of the cell-separation theory.
Effect of reserpine on excitability of the turtle heart
Authors: Stein Edward , Magin John , Kleinfeld Morris
Published: December 2017

The effects of reserpine on the cardiac excitability of the atrium and ventricle were studied in the turtle. Reserpine in concentrations of 0.5 and 1.0 mg/kg was found to have a quinidine-like action on cardiac excitability. This was manifested by a prolongation of latency, an increase in duration of the absolute and relative refractory periods and an elevation of diastolic threshold. When compared to quinidine in similar dosage, reserpine was appreciably less active.
Morphological and physiological changes in the skin as a result of long exposure to cold
Authors: LeBlanc J.
Published: December 2017

Goats exposed throughout the year to environmental conditions prevailing in a temperate climate have shown in the winter time an increased thickness of the Malpighian and of the horny layers and a decreased response to a cold-immersion test. A significant increase in number of layers in the stratum corneum was observed, with electron microscope techniques, in rats exposed to cold for 8 weeks at 6°C.
Comparison in control and severely diabetic, alloxanized rats of phosphate fractions, glycogen and fat
Authors: Beatty Clarissa H. , Peterson Ruth D. , Bocek Rose Mary , West Edward S.
Published: December 2017

Homogeneous aliquots of powdered muscle were analyzed and levels of constituents calculated on a fat-free basis. When compared to muscle from control rats, muscle from severely diabetic, alloxanized rats showed a decrease in creatine phosphate, total acid soluble phosphate and total phosphate, with no change in inorganic phosphate, adenosine diphosphate plus adenosine triphosphate, or total acid soluble phosphate minus 7-minute hydrolyzable phosphate, creatine, noncollagenous protein or total nitrogen. There was an increase in the trichloroacetic acid extractable glycogen value in the muscle of the alloxan diabetic as compared to the control series. The concentration of fat in the muscle itself was higher in the diabetic than in the control series, although the total muscle fat had decreased in the diabetic series due to the decrease in percentage of body weight represented by muscle.
Physiological effects of carbon dioxide gas introduced into coronary arteries
Authors: Oppenheimer Morton J. , Stauffer Herbert M. , Soloff Louis A. , Durant Thomas M.
Published: December 2017

Carbon dioxide gas is well tolerated when introduced directly into coronary arteries of anesthetized dogs. There were no fatalities in either normal or freshly infarcted hearts. Intracoronary carbon dioxide gas produced no persisting changes in the electrocardiogram or in blood pressure when injected slowly. Rapid injections under pressure produced extrasystoles at the time of injection and caused some subsequent changes of short duration in the electrocardiogram. These short duration changes were alterations of S-T segment deviations (which purposely had been produced previously in the control period) toward a more normal configuration. During this same period of time coupled extrasystoles produced in the control period were suppressed.
Small vessel responses of the dog paw
Authors: Davis D. L. , Hamilton W. F.
Published: December 2017

Pressures and flows were measured in small veins and arteries of the dog hind paw during stimulation of the ipsilateral lumbar sympathetic trunk. At stimulation frequencies less than 1–2/sec. the constrictor response was limited to very small arteries, or arterioles. Small artery pressure increased while small vein pressure and blood flow decreased. At stimulation rates from 1–2/sec. to 10/sec. small vein pressures were progressively increased while small artery pressures and blood flows were progressively decreased. At higher stimulation frequencies flow stopped, and small artery pressures fell to low levels (in many experiments to values well below the plasma oncotic pressure). Closure of arteries occurred at the ankle and a static column was formed which communicated with the capillaries. Simultaneously small vein pressure rose well above the oncotic level and was long maintained. The small vein walls were contracting against a static column of blood held between a strong constriction (closure?) at the ankle level and postcapillary venular valves (or constrictive closure). Since these high pressures occurred after flow had stopped they could not be relevant to transcapillary water shifts.
Epinephrine-induced hemoconcentration in the domestic hen
Authors: Tapper Daniel N. , Kare Morley R.
Published: December 2017

The effect of 150 µg/kg epinephrine intravenously on the packed cell volume (PCV) was studied in 24 laying hens. The PCV was observed to rise to a peak between 20 and 30 minutes after injection and to gradually return to the preinjection level after 1–2 hours. T-1824 disappearance curve analysis, repeated plasma volume determinations and direct red cell volume measurements, using Cr51-tagged red cells, substantiate the conclusion that the response is due to loss of fluid from the vascular system with resultant concentration of the erythrocytes already present. The possible relationship of the pressor effect of epinephrine and of the role of the kidney to the response is considered.
Comparative Effects of DL-Thyronine, L-Triiodothyronine and L-Thyroxine on the Isolated Perfused Frog Heart
Authors: Kleinfeld Morris , Rosenthal Albert , Stein Edward
Published: December 2017

Page 63: Morris Kleinfeld, Albert Rosenthal and Edward Stein, "Comparative effects of dl-thyronine, l-triiodothyronine and l-thyroxine on the isolated perfused frog heart." The name of the second author should read Alvin S. Rosenthal.
Metabolism of glutamic acid in the perfused rabbit heart
Authors: Doell Ruth G. , Felts James M.
Published: December 2017

The metabolism of C14-labeled glutamic acid by the isolated perfused heart was studied. Glutamic acid is readily assimilated by the normally beating heart and in the course of an hour's perfusion about 22% is oxidized to C14O2. Approximately 3.6% of the administered radioactivity is converted to glutamine. The utilization of glucose by the preparation is variable and not correlated with the concentration of glucose in the perfusate.
Role of histamine or other released substances in anaphylaxis in isolated guinea pig ileum
Authors: Dworetzky Murray
Published: December 2017

A study was made of the role of histamine or other active liberated substances in anaphylaxis in isolated segments of guinea pig ileum. A technique was used by which it can be quantitatively estimated how much of the total anaphylactic reaction is due to liberation of such substances. The method consisted of suspending a segment from a sensitized animal in a 40-ml bath, together with a segment called the ‘indicator segment’, from a normal, nonsensitized animal. Thus, during anaphylactic contraction of the sensitized segment, histamine or any other active substance liberated into the bath would be expected to diffuse through the perfusion bath and cause a contraction of the so-called ‘indicator segment’. The height of the contractions was roughly estimated in terms of that amount of histamine necessary to cause a contraction of the same intensity. Using this technique, it was concluded that no more than 10% of the total anaphylactic contraction in the isolated sensitized guinea pig ileum can be accounted for by histamine or any other substance liberated into the bath fluid.
Effect of estrogen and progesterone on water and electrolyte content of rabbit uteri
Authors: Bitman Joel , Cecil Helene C. , Hawk H. W. , Sykes J. F.
Published: December 2017

Estrogen, either endogenous or exogenous, caused an uptake of water in the rabbit endometrium. Endometria of rabbits in estrus or of spayed rabbits treated with estrogen had an extracellular compartment which was twice as large as the intracellular phase A similar distribution of water was observed in the endometria of ovariectomized control rabbits. Progesterone caused a complete reversal in the distribution of the endometrial water. Thus, pseudopregnant or progesterone-treated rabbit endometria had an intracellular phase which was twice as large as the extracellular compartment. Changes in Na and K concentrations were associated with these shifts in water between the exterior and interior of the cells. Endometria of progesterone-treated or pseudopregnant rabbits had high K and low Na concentrations in comparison to the estrous, estrogen-treated or ovariectomized rabbit endometria. Expressed as total K/Na ratios, the endometria showed extreme differences, being 0.54 under estrogen domination and 1.38 under progesterone influence.
Effect of thiamine deficiency on canine gastric secretion of acid
Authors: Lavers Marjorie K. , Stefanik Patricia A. , Code Charles F.
Published: December 2017

A study was undertaken to determine the effect of thiamine deficiency on the hydrochloric acid output of vagally denervated gastric pouches (Heidenhain-type) and vagally innervated gastric pouches (Pavlov-type) in dogs. Responses of both types of pouches to injection of 0.05 mg of histamine/kg of body weight and the maximal secretory capacity of both types after histamine were unaltered during the deficiency state. A degree of thiamine deficiency sufficient to produce anorexia and neuritis was without effect on the secretory response of canine gastric mucosa to histamine. The hydrochloric acid output of vagally innervated pouches during nervous stimulation caused by insulin-induced hypoglycemia was drastically reduced as soon as thiamine deficiency developed, while the response to bethanechol chloride was little, if at all, affected. It is concluded that the vagal secretory mechanism participates in the general neural failure of thiamine deficiency and that this failure most likely is in the neurons of the vagal nuclei.
Effects of iodoacetate on potassium, glucose and lactic acid metabolism in isolated perfused frog liver
Authors: Craig Albert B.
Published: December 2017

Iodoacetate (IAA) caused a decreased lactic acid production and increased glucose and potassium losses in the isolated perfused frog liver. These effects of IAA are compared to those of epinephrine which increased lactic acid production as well as causing glucose and potassium losses. Interpretation of these results is based on the assumption that both agents will cause an increase in the concentration of hexosemonophosphates, an event which may be associated with potassium loss from the liver.
Acid-base alterations and plasma potassium concentration
Authors: Simmons Daniel H. , Avedon Melvin
Published: December 2017

Arterial pH of anesthetized dogs was held constant during infusion of HCl or NaHCO3 by appropriate alterations in alveolar ventilation. While plasma potassium concentration dropped somewhat (presumably due to gradual potassium depletion), there was no significant difference in plasma potassium during the two types of infusions. The implication is that metabolic and respiratory acid-base disturbances having comparable effects on pH also have similar effects on the plasma potassium concentration. Other data support this conclusion and also indicate that effects of acidosis and alkalosis are quantitatively similar. On the basis of data of this study and of other data in the literature, it appears that the ratio of change in potassium concentration to change in blood pH ordinarily averages –3.0 to –5.0 in a steady state and that achieving a steady state requires 1–2 hours of equilibration. Data are presented which support the concept that extracellular K concentration, rather than total extracellular K, is physiologically regulated and that this involves rapid exchanges with intracellular K.
Acute effects of hypophysectomy and diencephalic lesions on aldosterone secretion
Authors: Davis James O. , Bahn Robert C. , Yankopoulos Nicholas A. , Kliman Bernard , Peterson Ralph E.
Published: December 2017

Acute effects of hypophysectomy and of diencephalic lesions on aldosterone and corticosterone secretion were studied in 10 dogs with chronic experimental ascites. During preliminary observations, diencephalic lesions were made by the oral approach but the pituitary gland was damaged; in two dogs aldosterone and corticosterone secretion fell markedly. In the third animal, ACTH was given following the lesion; aldosterone failed to fall while corticosterone declined slightly. In the definitive study (7 dogs), hypophysectomy was performed before the diencephalic lesion was made. Following hypophysectomy, a 76–97% decrease in aldosterone secretion occurred within 2 hours. The effects of diencephalic lesions were variable; aldosterone output was unchanged, increased, decreased and increased during the 1st hour but declined thereafter. Corticosterone secretion fell 81–99% after hypophysectomy. These acute observations show a striking dependence of aldosterone and corticosterone secretion upon intact pituitary function. The evidence on the relation of the diencephalon to aldosterone secretion was inconclusive but an intact middle and posterior hypothalamus was not essential for normal or elevated rates of aldosterone secretion.
Trophic maintenance of the diaphragm by various nerves
Authors: Jefferson N. C. , Ogawa T. , Toman J. , Scruggs W. , Necheles H.
Published: December 2017

In dogs, the central end of the cut phrenic or vagus nerve was anastomosed to the distal end of the phrenic nerve. After phreno-phrenic anastomosis, slight atrophy of the muscle and nerve elements of the diaphragm occurred up to 7–8 weeks, followed by regeneration. At that time, electric stimulation of the nerve above the anastomosis produced contraction of the diaphragm, although respiratory function was absent. Ten to eleven weeks after anastomosis, spontaneous respiration recurred. In the case of vagophrenic anastomosis, spontaneous respiration did not reappear within 58 weeks, but stimulation of the vagus above the anastomosis produced contraction of the diaphragm, and histologic study showed regeneration of muscle and nerve elements. It is concluded, that trophic maintenance of the diaphragm depends on the presence of functionable innervation, not necessarily on functioning innervation.
Oxygen lack as a possible cause of reactive hyperemia
Authors: Crawford Dewitt G. , Fairchild Hilton M. , Guyton Arthur C.
Published: December 2017

The relationship of blood flow through the hind leg of a dog to the gaseous content of the blood has been studied in 20 dogs by two different methods. In 15 dogs the oxygen saturation of the blood flowing through the leg was gradually changed by adding various amounts of venous blood to arterial blood. As the oxygen saturation decreased the blood flow increased—slowly at first, then progressively more rapidly as the oxygen levels fell lower and lower. Even though the oxygen saturation in most experiments was decreased to 30%, the total oxygen transported to the tissues each minute (O2 saturation times blood flow) decreased only to 75% of the control value. This showed that a definite compensatory mechanism exists, with an efficiency of about 65% for preventing tissue hypoxemia. In five animals the oxygen saturation of the blood was maintained constant while the dogs were allowed to breathe 20% carbon dioxide for an hour. By checking the blood flow every 10 minutes it was found that there was no increase in blood flow but rather in three of the animals a decrease to the extent of 35% of the control blood flow and in the remaining two no change. These studies indicate that oxygen deficiency might well be one of the causes of reactive hyperemia but that excess carbon dioxide probably is not involved.
Anemia of induced anaplasmosis in the calf
Authors: Hansard Sam L. , Foote Lon E.
Published: December 2017

Hematologic studies of periodic peripheral blood samples were employed to determine the onset and to follow the progress of induced anaplasmosis anemia in 33 young dairy calves. Total blood, red cell production and destruction were studied with iron-59 and chromium-51 concurrently at periodic intervals before, during and following anemia development. A marked and progressive decrease in RBC volume and hemoglobin, and a significant increase in the ratio of total plasma to RBC were noted as the disease developed. Plasma iron disappearance ( T1/2) increased and RBC iron turnover rate and utilization decreased markedly 3–10 days before peak marginal RBC bodies were evidenced. Results substantiate an initial suppression of the hematopoietic system and decreased iron utilization, reflecting the observed red cell and hemoglobin reductions as the disease progressed. Recovery, as evidenced by iron utilization, was rapid following disappearance of red cell marginal bodies from peripheral circulation, but red cell life span continued to decrease indicating production of short-lived cells. The progressive and variable nature of the anemia implied a more direct relationship to red cell production than to iron utilization.
Action of anti-inflammatory agents on endotoxin-induced lung inflammation in mice
Authors: Herrmann Ernest C. , Engle Claire , Perlman Preston L.
Published: December 2017

The instillation of Escherichia coli endotoxin (lipopolysaccharide) intranasally into mice produced severe lung lesions and a substantial increase in lung weight. Lung inflammation was maximal about 3 days after endotoxin instillation. Intraperitoneal injection of prednisone, cortisone and hydrocortisone sharply suppressed the lung inflammation. Five milligrams of prednisone produced a maximal anti-inflammatory effect when injected 24 and 48 hours after the endotoxin. Administration of large doses of Butazolidin also produced a modest effect on the lung inflammation. It is suggested that locally applied endotoxin alters blood vessel permeability of the lungs, resulting in hemorrhage, edema and exudation. The anti-inflammatory steroids reverse or inhibit this effect, perhaps by maintaining the integrity of the capillaries. Possible use and significance of this experimental anti-inflammatory system is discussed.
Nerve fiber activity in heavy water
Authors: Spyropoulos C. S. , Ezzy M. E.
Published: December 2017

Replacement of normal Ringer's surrounding the node of Ranvier of Bufo marinus with Ringer's prepared with D2O instead of H2O resulted in an increase in the duration of the response. In the squid giant axon immersed in D2O a rise in threshold membrane potential and a prolongation of the spike potential were observed.
Formation of albumen precursors by the hen's oviduct
Authors: Smith Arthur H. , Court Sandra A. , Martin Eugene W.
Published: December 2017

The composition of the oviduct magnum (albumen-forming segment) was determined before and after albumen deposition, and in nonovulating hens. The quantity and composition of material accumulated in the magnum after albumen deposition, but with and without subsequent ovulation, indicate that albumen precursors are formed in at least two steps. A large part, perhaps 45%, of the albumen deposited by the magnum appears to be synthesized and transferred at the time of deposition.
Tendon water and electrolyte and saccharide spaces in normal versus adrenalectomized rats
Authors: Audia Marino
Published: December 2017

Tendon chloride space in normal and adrenalectomized rats is equal to tendon water. Sodium space is about 81% of tendon water in normal rats and about 68% in adrenalectomized rats. Inulin space at 24 hours remains well below both sodium and chloride spaces; sucrose space at 24 hours is about as high as sodium space, but well below chloride space. One hour after injection tendon water is less penetrated by sucrose or inulin in adrenalectomized than in normal rats, but at 8 hours and 24 hours there is no significant difference between adrenalectomized and normal.
Effect of D2O in vivo and in vitro on uptake of p-aminohippurate by rat kidney slices
Authors: Thomson John F. , Klipfel Florence J.
Published: December 2017

Kidney slices from rats in which one-third of the body water was replaced by D2O showed no impairment of the capacity to accumulate PAH, despite the moribund condition of the animals. In vitro, 100% D2O inhibited PAH uptake by 65%, oxygen consumption by only 15%, during a 1-hour incubation of kidney slices; very little PAH was taken up after the first 30 minutes.
Effect of injections of hypertonic solutions on blood flow through the femoral artery of the dog
Authors: Marshall Robert J. , Shepherd John T.
Published: December 2017

Blood flow through the femoral artery was measured in 10 dogs; a bubble flowmeter was used in 5 and, in the other 5, an ultrasonic flowmeter was used. Rapid injections of 2 ml of 10–20% solution of NaCl caused a definite but transient reduction in flow, followed by a prolonged twofold to threefold increase. Similar effects were noted with other Na salts and also with 25–50% dextrose solution. The use of 25 and 50% solutions of urea caused only a prolonged increase in flow. Isotonic NaCl solution had little or no effect. Continuous infusions at 2.3 ml/min. of 10 and 20% solution of NaCl and 50% dextrose and urea solutions caused only doubled to tripled increase in flow which continued throughout infusion. The initial reduction in flow cannot be explained by reduction in perfusion pressure and may result from reversible hemagglutination in small vessels. The increase in flow is due to vasodilatation locally mediated, since it could not be accounted for by changes in perfusion pressure and was unchanged after denervation of the leg. The mechanism of the dilatation is uncertain, but since it occurs with salt-free hypertonic solutions it is not specific for sodium-containing salts.
Continuous recording of pulmonary blood volume: pulmonary pressure and volume changes
Authors: Lindsey Arthur W. , Guyton Arthur C.
Published: December 2017

A method for continuous recording of pulmonary blood volume in the intact animal has been devised, utilizing the detection of I131-tagged blood from a circumscribed portion of lung field. To rule out the interference of blood in the chest wall the counts per minute (cpm) obtained from the chest wall after removing the lung at the end of the experiment were subtracted from the recorded cpm throughout the experiment. The cpm from the chest wall were found to be stable, so that it was concluded that changes in total cpm were caused by changes in pulmonary blood volume. Constriction of the ascending aorta or pulmonary artery by previously placed loops of plastic tubing produced either right or left heart failure. When left heart failure was produced acutely, the pulmonary blood volume increased an average of 79.5%±6.1 S.E. in 23 dogs. Constriction of the pulmonary artery, producing acute right heart failure, decreased the pulmonary blood volume an average of 38%±2.3 S.E. in 23 dogs.
Membrane depolarization as a cause of tension development in mammalian ventricular muscle
Authors: Kavaler Frederic
Published: December 2017

A method was devised which made it possible to depolarize ventricular muscle, over a short interval of length, by applying an external voltage and to record, from the same segment, the developed tension. A fiber bundle, 0.5–1.0 mm in diameter, from the right ventricular cavity of the sheep or calf, was inserted into a close-fitting hole in a plastic block, contained in a Tyrode bath. The fibers were depolarized where they exited from the block. The muscle was held, by suction, at two surface points of very small area, 0.4 mm apart. Measurements with microelectrodes showed that the depolarization was roughly uniform over the length of muscle segment from which tension was recorded. By this means, the action potential (normally lasting about 1/2 sec.) could be prolonged to a duration of 2 seconds. This caused tension to be maintained at near-peak levels; relaxation occurred only when the fibers were allowed to repolarize. Evidence was thus adduced in support of the view that the contractile mechanism is continuously responsive to depolarization.
Transport of potassium-42 from blood to tissue in isolated mammalian skeletal muscles
Authors: Renkin Eugene M.
Published: December 2017

A method is described for studying transcapillary diffusion of K42 in isolated perfused muscles of dogs. Blood flow and arteriovenous K42 differences are measured and blood-tissue clearance calculated by the Fick principle. A theoretical relation between blood flow and blood-tissue clearance is developed for a uniform circulation characterized by a constant permeability—surface area product (PS). The experimental observations conform reasonably closely to prediction. However, systematic variation in measured PS product with changes in blood flow and vascular resistance indicate that the capillary circulation is not uniform.
Sodium glucuronate and glucuronolactone in bilirubin conjugation and formation of borneol glucuronide
Authors: Driscoll Shirley G. , Hsia David Y. Y. , Dennen David A. , Dowben Robert M.
Published: December 2017

Sodium glucuronate, glucuronolactone or glucose labeled uniformly with radiocarbon was administered intravenously to dogs together with an intravenous infusion of bilirubin. When sodium glucuronate was injected, the bile recovered in the succeeding 3 hours contained 4.16 x 10–6 and 8.33 x 10–7 of the labeled material injected per milligram bilirubin. Recoveries after injection of labeled glucuronolactone were 4.98 x 10–5 and 7.94 x 10–5 of the administered label per milligram bilirubin excreted, and when labeled glucose was given, the fractions recovered were 3.39 x 10–4 and 4.91 x 10–4/mg bilirubin. Radioautograms of paper chromatograms of bile showed radioactivity at the spots corresponding to bilirubin glucuronide when glucose was the labeled substrate. An average of 0.89% glucuronolactone-1-C14 given together with borneol to rats appeared in the borneol glucuronide isolated from urine. When glucuronolactone-6-C14 was used as substrate, the incorporation into borneol glucuronide was not significant. These data are interpreted to indicate the incorporation of a very small but definite fraction of administered glucuronolactone into glucuronide conjugates via an indirect pathway; significant direct incorporation does not occur in the intact animal. However, glucose is a more effective precursor of bilirubin glucuronide than glucuronolactone.
Inhibition of cholesterol biosynthesis by cholic acid
Authors: Beher William T. , Baker Gizella D.
Published: December 2017

The effects of dietary cholic acid on free, total and ester cholesterol levels in liver and serum, and on the relative rates of incorporation of acetate-1-C14 and mevalonic acid-2-C14 were investigated in the rat. Cholic acid caused equally significant increases in free and ester liver cholesterol. No significant changes were found in serum cholesterol levels. The incorporation rate of acetate-1-C14 into liver and serum cholesterol was inhibited by 65% when cholic acid was fed to rats, while the inhibition of mevalonic acid-2-C14 incorporation was 25%. It is suggested that cholic acid inhibits cholesterol biosynthesis between mevalonic acid and cholesterol, or retards the entire series of reactions between acetate and cholesterol.
Development of cecal distention in germ-free baby rats
Authors: Wostmann Bernard , Bruckner-Kardoss Edith
Published: December 2017

The weight of the full cecum was determined in normal-born, mother-fed, germ-free and conventional rats during the lactation period and shortly thereafter. Compared to conventional rats of the same age, the germfree animals showed an increase in cecal weight which started during the 2nd week of life. Even with mother's milk as a sole source of nourishment up to 25 days of age, the cecum of the germ-free animals at that time already had reached the degree of distention seen in older germ-free rats. Germ-free rats fed semisynthetic and practical diets in general show a five- to sevenfold increase in cecal weight, compared to conventional animals. It is concluded that the absence of stimulation by a microbial flora, rather than a nutritional deficiency due to sterilization of the diet is the prime etiological factor in this phenomenon.
Tolerance of cooled animals to acute hypoxia during rewarming
Authors: Davidović J. , Wesley Ines
Published: December 2017

Rats cooled to a rectal temperature of 20°C were permitted to rewarm at a simulated altitude of 11,500 m. A greater survival rate was observed in animals so treated than in controls not previously exposed to hypothermia. The loss of hypoxic tolerance was more pronounced within the range of 28°–36°C than in the range of 22°–28°C. The depth of cooling has a notable influence on the tolerance to hypoxia during rewarming when the body temperature of 33°C is reached. Thus far, the most resistant were rats cooled by the closed vessel technique to 18°C and those cooled by immersion to 22°C. The mechanism of this interesting phenomenon is unknown.
Quantitative measurement of erythropoiesis in the dog
Authors: Weissman S. M. , Waldmann T. A. , Berlin N. I.
Published: December 2017

The quantitative measurement of erythropoiesis requires the simultaneous determination of total red cell volume, rate of production of red cells and the red cell life span. The total red cell volume was measured with autologous Cr51-labeled red cells, the rate of production of red cells from the rate of disappearance of radioiron from the plasma and uptake by red cells, the red cell life span with C14-labeled glycine and the apparent red cell survival T1/2 with Cr51. The average total red cell volume of the dogs studied was 38.6 cc/kg; the plasma radioiron T1/2 was 66 minutes; the red cell radio-iron uptake was 80%; the serum iron was 102 µg/100 cc, and the plasma volume calculated from the peripheral hematocrit and total red cell volume was 46 cc/kg, and from the extrapolation to t0 of the radioiron disappearance was 48 cc/kg. From these figures the plasma iron turnover was calculated to be 0.63 mg/kg/day and the red cell iron renewal rate 1.26%/day. The average red cell life span was 108 days; the average apparent T1/2 of Cr51 red cell survival was 24.3 days; the average elution rate of Cr51 was 1.77%/day.
Rate of cerebral ATP utilization in rats
Authors: Samson Frederick E. , Balfour William M. , Dahl Nancy A.
Published: December 2017

The rate of adenosinetriphosphate (ATP) disappearance in the brain after inhibition of aerobic and anaerobic metabolism was investigated. It was found that the rate increases with increasing age in the neonatal rat and that the effect of lowering the body temperature, which slows the rate, is greater in the 21-day rat than in the newborn. Calculation from the data gives 0.5 µm/sec/gm as the rate of high-energy phosphate utilization in the 21-day rat, and 0.04 µm/sec/gm in the 1-day rat. This increase in the rate of energy utilization during neonatal maturation is compared with the capacity to generate ATP; the utilization increase is found to be six times that of the capacity to generate ATP. The Q10 of the high-energy phosphate utilization in the 21-day rat is 1.7 in the 37°–25°C range, but is 10. in the 25°–15°C range. It is concluded that the rate of high-energy phosphate utilization is closely related to the amount of neuronal activity and, further, that the energy cost per average nerve impulse probably is greater in the adult brain than in the neonatal brain.
Oxygen availability in brain tissues after lipid meals
Authors: Swank Roy L. , Nakamura Haruomi
Published: December 2017

The available oxygen in the hamster's brain was studied polarographically employing the platinum electrode technique. The electrodes were permanently implanted. After large lipid meals, the amount of oxygen available in the tissues was reduced. The reduction was greatest after cream and another highly saturated fat mixture. It was least after the very unsaturated oils, safflower and cod liver oils. Changes after olive, corn, cottonseed and other vegetable oils were intermediate. Cream meals containing as little as 0.9 gm of lipid/kg body weight produced significant reductions in the available oxygen in the tissues. Our studies suggest that the decrease in available oxygen in the tissues was due primarily to the amount of the saturated fatty acid in the lipid feeding.
Effects of pH changes on O2 uptake and plasma catecholamine levels in the dog
Authors: Nahas G. G. , Ligou J. C. , Mehlman B.
Published: December 2017

During hypercapnic acidosis induced by ‘apneic oxygenation,’ one observes in the dog a rise in plasma catecholamine levels in the presence of a constant oxygen uptake (Qo2) and a rise in mean blood pressure. When pH is maintained constant or alkaline by infusion of T.H.A.M. (2 amino 2 hydroxymethyl 1–3 propane diol), Qo2 remains constant while plasma catecholamines and blood pressure do not change although total plasma CO2 shows a twofold increase. When blood pH is rapidly shifted from 6.99 ± .03 to 7.52 ± .02, Qo2 increased by 39%, while plasma catecholamine levels were rapidly re-established to normal. The infusion of 1 µg/kg/min. of epinephrine, norepinephrine or isoproterenol will also produce a significant increase in Qo2 and blood pressure in the apneic dog when arterial blood pH is maintained normal or alkaline; but the same dose of epinephrine fails to change significantly Qo2 or blood pressure when arterial blood pH is maintained between 6.97 and 7.28.
Effect of external potassium concentrations, insulin and lactate on frog muscle potassium and respiratory rate
Authors: Smillie L. B. , Manery J. F.
Published: December 2017

In Ringer's solution containing 10 mEq K/l., frog muscles consumed oxygen at 20°C at rates ranging from 88 (summer frogs) to 128 (winter frogs) cu mm/gm/hr. These rates, which were three to four times higher than those at 2 and 6 mEq K/l., continued to rise for at least 6 hours, although the muscles had previously been soaked at 5°C in the type of Ringer's in which they respired. Addition of lactate increased the respiratory rate at all K concentrations studied. When insulin was present a marked additional stimulation was observed at 2 and 6 mEq K/l., which was changed to an inhibition at 10 mEq/l. Potassium analyses of all of the environmental fluids and of the muscles (144 of each) demonstrated a slight K loss from control muscles which was reduced or abolished by lactate. Insulin, however, either with or without added lactate, abolished the K loss and induced an appreciable K uptake. This K gain occurred regardless of the effect of insulin on the respiratory rate. Denaturation of the insulin abolished all of its effect. Seasonal differences were noted.
Potassium transport in isolated guinea pig ileum
Authors: Hurwitz Leon
Published: December 2017

A study was carried out to characterize the transport of potassium ions across the smooth muscle membrane of the isolated guinea pig ileum. The relative magnitudes of unidirectional ion fluxes were followed by employing the radioactive tracer K42. In unstimulated tissues both the efflux and influx of potassium were found to be proportional to the total quantities of exchangeable ion present in the tissue and in the surrounding medium respectively. The addition of approximately 7.5 x 10–6 m pilocarpine, a concentration which produced a maximal contraction of longitudinal smooth muscle, increased potassium efflux about 100–150%, whereas potassium influx was markedly impeded. Cocaine (about 9 x 10–4 m) blocked the enhancement of potassium efflux induced by pilocarpine, but did not alter potassium efflux in the untreated tissue. The data suggest that the movements of potassium in excited smooth muscle fibers reflect, to a large extent, a permeability change either to sodium ions or some other ion species which exert a depolarizing influence on the cell membrane.
Effect of atropine and choline on urinary electrolytes
Authors: Solomon Sidney , Davis Betty Jane , Boone Owen Riley
Published: December 2017

Single injections of atropine (0.5 mg/kg) into dogs generally caused some antidiuresis which was accompanied by a reduction in glomerular filtration rate. Atropine-induced antidiuresis may be accompanied by a fall in UNa and UCl. Atropine protected dogs against the toxic action of subsequently infused choline. In seven experiments, choline caused UpH to rise and UNa to fall. In five of seven experiments UK also fell. The action of choline on UCl is variable. At high rates of infusion, choline appears to act as an osmotic diuretic.
Influence of oxytocin and vasopressin on sodium-retaining activity of aldosterone in the rat
Authors: Barnafi L. , Rosas R. , de la Lastra M. , Croxatto H.
Published: December 2017

Changes in water, sodium and potassium excretion were studied after injection of oxytocin, vasopressin and aldosterone. Normally hydrated and overloaded rats were used. Oxytocin, 2.5, 5.0 and 10.0 mu increased sodium and potassium output. The sodium retaining activity of 0.5 and 1.0 µg of aldosterone was abolished when used in combination with 2.5 and 5.0 mu oxytocin. The antidiuretic effect of 0.5–5.0 mu vasopressin was accompanied by an increase in sodium excretion; change in potassium excretion occurred only in the 2nd hour after the injection. Suitable doses of vasopressin were also able to counteract the effect of aldosterone on sodium retention.
Requirement for vitamin D for the active transport of calcium by the intestine
Authors: Dowdle Eugene B. , Schachter David , Schenker Harris
Published: December 2017

The active transport of calcium from the mucosal to the serosal surfaces of everted gut-sacs of the rat is dependent on the dietary vitamin D. The active transfer in vitro is significantly increased one hour following the administration of calciferol by gastric tube to rats depleted of the vitamin. Vitamins D2 and D3 are approximately equally effective, whereas dihydrotachysterol (A.T. 10) is somewhat more effective than either of the vitamins D. Ultraviolet irradiation of intact rats also increases the active transport of calcium in vitro. Maintenance on a low calcium diet increases the active transfer, whereas thyroparathyroidectomy decreases it. Vitamin D is required to demonstrate both of these effects clearly. The results support the hypothesis that the active transfer is an adaptive mechanism which ensures adequate absorption when the requirement for calcium is increased, or when the diet is low in calcium.
Brain blood flow, chlorpromazine (Thorazine) and its protective action against the toxicity of O2 at high pressure
Authors: Bean John W. , Wagemaker Herbert
Published: December 2017

The influence of Thorazine preparation of chlorpromazine on brain blood flow was studied in acute experiments by continuous direct recording (thermopile) in anesthetized (pentobarbital) dogs. Internal carotid injection of chlorpromazine (Thorazine) invariably increased brain blood flow promptly and sustained it for some time, with or without an attendant decrease in blood pressure. This is ascribed to a dilatatory action on vascular walls independent of antiepinephrine effects or adrenergic blockage of nervous influence. The carotid sinus and body are relatively insensitive to chlorpromazine (Thorazine) and are not essential to this response. Similar amounts intravenously injected failed to alter brain blood flow or respiration, but heavier doses increased respiration temporarily, probably due to a coincident transient decrease in blood pressure and flow and/or stimulation of reflexogenic zones. Brain blood flow was not significantly affected by intraperitoneal or intramuscular administration. The data provide no evidence that the protection against the toxicity of oxygen at high pressure by chlorpromazine (Thorazine) might be due to its hypotensive action and a presumptive consequential decrease in cerebral blood flow and oxygen supply to the CNS as previously suggested.
Excitability of spinal neurons and changes resulting from reticular formation stimulation
Authors: Ushiyama J. , Koizumi K. , Brooks C. McC.
Published: December 2017

The threshold of spinal motoneurons and interneurons to direct stimulation was tested by applying current pulses through an intracellular microelectrode. Membrane potentials and cellular responses were recorded from the same penetrating microelectrode. Reactions of these neurons to orthodromic (afferent nerve stimulation) and antidromic impulses (ventral root stimulation) were determined. Reflex responses were recorded from ventral roots. Reticular formation stimulation resulting in inhibition of reflex action caused an increase in the thresholds of spinal neurons. Facilitory reticular formation action had more of a mixed effect on these neurons but in a considerable percentage thresholds were lowered. The percentage of neurons thus affected varied as did the magnitude of reticular formation effect on reflex action in the spinal segment under study.
Dental changes induced in rats by chronic exposure to adverse environments
Authors: Harris Norman O. , Mefferd Roy B. , Restivo Salvatore R.
Published: December 2017

The histology and chemical composition of teeth were examined from rats acclimated for 18–24 weeks to cold (3°C), neutral (24°C) or heat (36°C), at barometric pressures of either 750 or 380 mm Hg. There were negligible histological changes in cold alone, but altitude induced changes in the mesenchymal elements of the teeth. These were made more severe by superimposed cold, but superimposed heat counteracted some of these effects. In the latter group, however, there were ectodermal changes. Chemical studies on these teeth revealed significantly reduced concentrations of calcium, phosphate and magnesium in the altitude- and heat-exposed rats. The cold-acclimated rats, as was the case histologically also, did not differ from the controls. Protein and iron content did not differ significantly among the groups. There were significant changes in the ratios of calcium, magnesium and phosphate. Possibly the basic inorganic composition of the teeth of altitude acclimated rats was changed since the Ca/PO4 ratio was low. X-ray diffraction failed to confirm this, however.