bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of a chronic high-salt diet on large artery structure: role of endogenous bradykinin
Authors: Partovian Chohreh , Benetos Athanase , Pommiès Jean-Pierre , Mischler Willy , Safar Michel E.
Published: December 2017

Bradykinin activity could explain the blood pressure increase during NaCl loading in hypertensive animals, but its contribution on vascular structure was not evaluated. We determined cardiac mass and large artery structure after a chronic, 4-mo, high-salt diet in combination with bradykinin B2-receptor blockade by Hoe-140. Four-week-old rats were divided into eight groups according to strain [spontaneously hypertensive rats (SHR) vs. Wistar-Kyoto (WKY) rats], diet (0.4 vs. 7% NaCl), and treatment (Hoe-140 vs. placebo). In WKY rats, a high-salt diet significantly increased intra-arterial blood pressure with minor changes in arterial structure independently of Hoe-140. In SHR, blood pressure remained stable but 1) the high-salt diet was significantly associated with cardiovascular hypertrophy and increased arterial elastin and collagen, and 2) Hoe-140 alone induced carotid hypertrophy. A high-salt diet plus Hoe-140 acted synergistically on carotid hypertrophy and elastin content in SHR, suggesting that the role of endogenous bradykinin on arterial structure was amplified in the presence of a high-salt diet.
Attenuation of vascular relaxation after development of tachyphylaxis to peroxynitrite in vivo
Authors: Benkusky Nancy A. , Lewis Stephen J. , Kooy Neil W.
Published: December 2017

Peroxynitrite, formed endogenously by the near diffusion-limited reaction of nitric oxide with superoxide anion, induces vascular relaxation. This effect is subject to rapid tachyphylaxis, suggesting that peroxynitrite may alter subsequent vasorelaxant responses. The present study examined the effects of peroxynitrite on mean arterial pressure and hindquarter, renal, and mesenteric vascular resistances in pentobarbital-anesthetized rats. Peroxynitrite induced dose-dependent decreases in mean arterial pressure and hindquarter and mesenteric vascular resistances. The repetitive administration of peroxynitrite resulted in the rapid development of tachyphylaxis, with subsequent doses producing progressively smaller effects. After the development of tachyphylaxis to peroxynitrite, the hemodynamic effects produced by the systemic administration of acetylcholine and prostacyclin were significantly attenuated, whereas the hemodynamic responses to bradykinin and the nitric oxide donor ( Z)-1-{ N-methyl- N-[6( N-methylammoniohexyl)amino]}diazen-1-ium-1,2-diolate (MAHMA NONOate) remained unchanged. These results demonstrate that 1) peroxynitrite is a potent vasorelaxant in vivo, 2) peroxynitrite-mediated vasodilatation is subject to the development of rapid tachyphylaxis, and 3) peroxynitrite alters the vascular smooth muscle response to prostacyclin, perhaps via inactivation of vascular smooth muscle ATP-sensitive potassium channel function.
Mechanisms of pH preservation during global ischemia in preconditioned rat heart: roles for PKC and NHE
Authors: Rehring Thomas F. , Shapiro Joseph I. , Cain Brian S. , Meldrum Daniel R. , Cleveland Joseph C. , Harken Alden H. , Banerjee Anirban
Published: December 2017

Ischemic preconditioning (PC) attenuates cardiac acidosis during global ischemia. This adaptation to ischemia is detectable before other better known indexes of PC are manifested. Clarification of the endogenous mechanisms may provide insights into how protein kinase C (PKC) signaling might be linked to altered intracellular biochemistry.31P NMR studies of isolated, buffer-perfused rat heart were performed to determine whether functionally cardioprotective PC by cyclic ischemia (CI) and α1-adrenergic stimuli [phenylephrine (PE)] attenuated acidosis during ischemia and, if so, whether this 1) involves a PKC-dependent pathway and is due to 2) decreased glycolytic proton production, 3) an increase in proton buffering, or 4) proton extrusion. At the end of 20 min of global ischemia, both CI-PC (pH = 6.86 ± 0.14) and PE-PC (pH = 6.90 ± 0.13) attenuated end-ischemic acidosis (control pH = 6.54 ± 0.1). PKC blockade with chelerythrine (Chel) prevented the attenuation of ischemic acidosis by PC stimuli (end-ischemic pH: CI + Chel, 6.43 ± 0.06; PE + Chel, 6.17 ± 0.17). End-ischemic lactate accumulation was decreased in CI-PC hearts (7.54 ± 0.5 vs. control, 14.61 ± 2.1 μmol/g wet wt) but not in those preconditioned through the α1-adrenergic receptor (12.25 ± 0.9 μmol/g wet wt). Physiologically relevant buffers were not increased in the preconditioned groups. Blockade of the Na+/H+exchanger [NHE; with 5-( N-ethyl- N-isopropyl) amiloride (EIPA) or HOE-694] eliminated the attenuation of ischemic acidosis seen with PC stimuli (pH: CI + EIPA, 6.5 ± 0.1; PE + EIPA, 6.46 ± 0.2; PE + HOE-694, 6.26 ± 0.15; not significantly different from control). We conclude that CI and α1-adrenergic PC stimuli attenuate ischemic acidosis, and this may involve the cardiac amiloride-sensitive NHE. The signaling pathways of both these two stimuli appear to involve PKC.
Responses of muscle sympathetic nerve activity to lower body positive pressure
Authors: Fu Qi , Sugiyama Yoshiki , Kamiya Atsunori , Shamsuzzaman A. S. M. , Mano Tadaaki
Published: December 2017

To evaluate the response of vasomotor sympathetic nerve activity to lower body positive pressure (LBPP), muscle sympathetic nerve activity (MSNA) was microneurographically recorded from the tibial nerve in 10 healthy young men, along with hemodynamic variables and echocardiogram, during exposure to incremental LBPP at 10, 20, and 30 mmHg in the supine position. MSNA was suppressed to a similar extent (27%) at 10- and 20-mmHg LBPP. However, at 30-mmHg LBPP, MSNA tended to increase but was still nearly at the control value. Mean arterial pressure was elevated (11%), total peripheral resistance markedly increased (36%), and stroke volume and cardiac output tended to decrease at 30-mmHg LBPP. Heart rate remained unchanged throughout the procedures. Left atrial dimension significantly increased during 10- and 30-mmHg LBPP, indicating an increased cardiac filling. These results suggest that the inhibitory effect of the cardiopulmonary baroreflex on MSNA at 10- and 20-mmHg LBPP could be counteracted by the sympathoexcitatory effect of the intramuscular pressure-sensitive mechanoreflex at 30-mmHg LBPP. However, the increment of total peripheral resistance at 30-mmHg LBPP may not depend exclusively on this small enhancement of MSNA.
Effects of isoflurane on [Ca2+]i, SR Ca2+ content, and twitch force in intact trabeculae
Authors: Jiang Yandong , Julian Fred J.
Published: December 2017

The goal was to test whether isoflurane exerts its depressant effect on the heart by mainly affecting the intracellular Ca2+ transient [Ca2+]i. Intact rat ventricular trabeculae, paced at 0.5 Hz and 30°C with extracellular [Ca2+] ([Ca2+]o) of 2 mM, were used. The [Ca2+]iwas monitored using fura 2 injected into the myoplasm. The sarcoplasmic reticulum (SR) Ca2+ content was estimated using rapid cooling with or without caffeine to induce Ca2+ release and contracture. A plot of peak twitch force versus peak [Ca2+]itransient with increasing isoflurane concentration declines linearly so that a 56% reduction in the peak [Ca2+]itransient would abolish twitch force. This relationship is intermediate between those obtained with lowering [Ca2+]o, which depresses twitch force through a reduction of the [Ca2+]itransient, and adding 2,3-butanedione monoxime, which reduces the responsiveness of the contractile system to [Ca2+]i. The isoflurane effect is different from that of halothane with respect to both the above relationship and the rapid-cooling response. Isoflurane abolishes the ability of rapid cooling to liberate Ca2+ from the SR.
Effects of Carbon Dioxide and Oxygen on Properties of Experimental Seizures in Mice
Authors: Woodbury Dixon M. , Rollins Lawrence T. , Henrie Joyce R. , Jones Joseph C. , Sato Tada
Published: December 2017

The influence of various concentrations of carbon dioxide and oxygen on the pattern of maximal electroshock seizures (MES), on pentylenetetrazol (Metrazol)-induced seizures, and on recovery time (RT50) from MES has been studied in mice. The major results are summarized as follows: Increasing the concentration of carbon dioxide in 20% oxygen resulted in marked changes in the MES pattern. The duration of the tonic flexor component was increased, and the duration of the tonic extensor component and of the entire tonic phase was decreased; the ratio of flexion to extension was increased markedly. These changes indicate an anticonvulsant effect of carbon dioxide. Carbon dioxide in a concentration of 15.6% protected 50% of mice against a 97% convulsant dose (CD97) of Metrazol. Hypoxia, induced by inhalation of 15 or 10% oxygen, decreased the duration of the tonic flexor component and increased the duration of the tonic extensor component of the MES; the duration of the entire tonic phase was increased; the ratio of flexion to extension was slightly decreased. These changes indicate an excitatory effect of low oxygen concentrations on the brain, under the stated conditions. Hyperoxia, induced by inhalation of 50, 75 or 90% oxygen, in contrast to hypoxia, resulted in effects on MES similar to those produced by inhalation of carbon dioxide. The RT50 was slightly, but not significantly, decreased by hypoxia (15% oxygen), unchanged by hyperoxia (50% oxygen), and markedly increased by an increase in carbon dioxide concentration. Carbon dioxide (5 and 10%) combined with hypoxia (10% oxygen) produced effects on MES pattern and RT50 similar to those produced by carbon dioxide in 20% oxygen.
Cortical Discontinuity and Propagation of Spreading Depression
Authors: Harreveld A. Van , Terres G. , Dernburg E. A.
Published: December 2017

The transmissibility of spreading depression across a cut severing all layers of the cortex was investigated in preparations in which 3 weeks to 3 months was allowed for healing of such an injury. No unequivocal signs of transmission of the spreading depression across the scar were observed, although in some instances the scar was less than 0.1 mm wide. In some experiments a small slow potential change was led off from the cortex on the nonstimulated side by an electrode placed in the immediate vicinity of the scar. This potential was considered as evidence for the physical spread across the scar of the potential field produced by the slow potential change which accompanies the spreading depression on the stimulated side. The failure of transmission of spreading depression across a scar does not support the concept that the slow potential change is the agent involved in the propagation of this phenomenon.
Changes in Nitrogenous Components of Brain Produced by Stimulation of Short Duration
Authors: Geiger Alexander , Yamasaki Seiichiro , Lyons Richard
Published: December 2017

Brain cortex of cats was stimulated through the brachial plexus for 5–30 seconds and the sensory motor area was frozen in situ, the contralateral area frozen 3 seconds before stimulation, serving as control. Stimulation for 20 seconds at 60 cpm produced the following chemical changes per gm wet tissue: a) nonprotein nitrogen increased by 16 µEq; b) nucleic acid nitrogen decreased by 10 µEq; c) lipid nitrogen decreased by 12 µEq. Amino-nitrogen increased in the lipid and nucleic acid fractions and decreased in the acid-soluble fraction. These chemical changes were proportional to the number of effective stimuli and were reversible at rest. It is concluded that nucleic acids and lipids are metabolized in the brain cortex during activity.
Cholinergic Mechanism of Brain Involved in Compulsive Circling
Authors: Aprison M. H. , Nathan P. , Himwich H. E.
Published: December 2017

Compulsive circling, directed either to the left or to the right, can be produced in rabbits by the injection of 0.05, 0.10 or 0.15 mg/kg of DFP into the right common carotid artery. A study of the effects of these doses of DFP on the ChE activity in the frontal cortex, caudate nucleus, superior and inferior corpora quadrigemini, and thalamus of circling animals has been presented. An asymmetric ChE pattern in the cortex and caudate nucleus was always associated with the involuntary circling behavior. However, no asymmetry in ChE activity was noted between corresponding posterior right and left brain areas (medulla, pons, cerebellum). In these experiments the vestibular nuclei were not involved in the production of forced circling. The injection of either ACh (10–100 µg/kg) or Mecholyl (25–50 µg/kg) through a ‘T’ shaped cannula inserted into the right common carotid artery produced forced turning movements of short duration in a majority of the cases. Although a few animals turned to the left, most rabbits circled to the right. These experiments present additional evidence for the intermediary role of ACh in the production of compulsive circling after the injection of DFP. The evidence suggests a cholinergic mechanism in the cerebral cortex and caudate nucleus for the production of forced circling in rabbits. An hypothesis based on the ChE activity in these structures has been presented which can explain why these animals exhibit forced turning movements under the experimental conditions.
Effect of Adrenalectomy on the Incorporation of Acetate Into Fatty Acids, Cholesterol and Acetoacetic Acid by Rat Liver Slices
Authors: Perry W. F. , Bowen Helen F.
Published: December 2017

The incorporation of C14 acetate into fatty acids, cholesterol, acetoacetic acid and CO2 by liver slices of intact and adrenalectomized rats was studied, the slices being incubated in bicarbonate and phosphate buffers. It was found that in both buffer systems incorporation into fatty acids and cholesterol was depressed while incorporation into acetoacetic acid was unaffected by adrenalectomy. However, total acetoacetic acid formation by the slices tended to be higher in preparations from adrenalectomized animals. The amount of acetate carbon appearing as CO2 was similar with slices from both types of animals. Bicarbonate was found to be a more favorable medium than PO4 for fatty acid formation, while PO4 was the more favorable medium for cholesterogenesis, though the differences between adrenalectomized and intact animals persisted in either buffer. Forced feeding with glucose increased the incorporation of acetate into fat and cholesterol in both buffer systems in adrenalectomized as well as in intact animals. However, the adrenalectomized preparation still incorporated acetate to a lesser extent than the controls. It was concluded that while the depressed incorporation of acetate into fatty acid and cholesterol by adrenalectomized liver slices was consistent with a depressed synthesis of these lipids, there was also the possibility that it reflected an increased turnover of lipids in the liver of the adrenalectomized animal.
Kidney Glutaminase and Carbonic Anhydrase Activities and Renal Electrolyte Excretion in Rats
Authors: Muntwyler Edward , Iacobellis Michael , Griffin Grace E.
Published: December 2017

The plasma electrolyte composition and 24-hour urine electrolyte excretion were determined in fasting normal, K-deficient and protein and K-deficient rats following the administration of equal molar quantities of NaCl, KCl, NH4Cl and KHCO3. An attempt was made to relate any differences in the compositions of the plasma and urine to the levels of renal glutaminase and carbonic anhydrase activities, and, to the chemical compositions of the skeletal muscle and kidneys. Renal glutaminase and carbonic anhydrase activities were found increased in K-deficiency and reduced in protein and K-deficiency. Significant changes from corresponding control levels of renal glutaminase were found in normal and K-deficient animals only after the administration of NH4Cl (increased), and, after the administration of KHCO3 (reduced). The only outstanding change of the carbonic anhydrase activity of the kidneys from these animals was a reduction following NH4Cl administration. The doubly deficient rats showed a significant increase in renal glutaminase activity after NH4Cl administration; on the other hand, KCl administration resulted in a further reduction of the lowered renal carbonic anhydrase activity. The experimental results supported the contention that a relationship exists between urinary ammonia excretion and the level of renal glutaminase activity, while the transfer of H+ to the urine and the level of renal carbonic anhydrase activity could not be related. No clear relationship was found between the K excretion and/or K content of the kidneys and the urine total titratable acidity and ammonia excretion, and urine ph.
Biphasic Effect of Pitressin on Sodium Tolerance in the Hypertensive Rat
Authors: Friedman Sydney M. , Nakashima Miyoshi , Friedman Constance L.
Published: December 2017

The effect of a large dose of Pitressin (2 iu subcutaneously) on Na and water excretion under load was studied in rats made hypertensive by DCA. This dose is calculated to be within the upper limit of physiological secretion by the neurohypophysis. The excretion pattern was determined during the 4 1/2 hours following gavage with 100 mg of NaCl in 3 cc of water, both for the period immediately following Pitressin administration and for the period 3 hours after administration. These two periods were selected as corresponding to the pressor and depressor phases of Pitressin action, respectively. The procedure was carried out after one, four and eight daily injections of Pitressin. The selection of control and hypertensive animals was based on a preliminary blood pressure determination obtained by direct electromanometry from the femoral artery. The experiments demonstrated that Pitressin at this dose level has a biphasic action on the handling of Na and water as it has on blood pressure. The first phase consists of a limited tendency to accentuate the already accelerated rate of Na and water excretion found in the hypertensive state. This first effect was not obtained after eight injections. The second phase is characterized by a marked decrease in Na and water excretion which appears to be independent both of the antecedent rate of Na and water loss and of the number of injections.
Use of Desoxyribonucleic Acid as a Reference Standard in Metabolic Experiments
Authors: Gray Doris E. , Deluca H. A.
Published: December 2017

The metabolic activity (as gauged by glycogen synthesis, glucose uptake and oxygen consumption per gram of wet tissue) was found to be increased in diaphragms taken from rats maintained on a low-protein diet compared to normal controls. There was no significant difference in these indices of metabolic activity when they were expressed on a per cell basis (calculated on the content of desoxyribonucleic acid phosphorus). In protein deprivation, the mass of the diaphragm cell was dependent upon the protein intake rather than the total caloric intake but the metabolic activity of the cell was independent of its mass. These findings suggest that the metabolic activity of a tissue may, under certain experimental conditions, be more suitably expressed on a per cell basis than on the more usual basis of wet weight of tissue.
Masking of Cortical Responses in Middle Ectosylvian Auditory Area of the Dog
Authors: Tunturi Archie R.
Published: December 2017

The masking of cortical responses in the middle ectosylvian (MES) auditory area of the dog was studied by oscillographic recording and by using noise, pure tones, the onset of pure tones and the ‘ p’ pulse for acoustic stimuli. Local applications of strychnine to the cortex were used to enhance the responses and thus obtain information from the strychninized portion of the cortex. The characteristic of the masking curve was a low frequency slope which was less steep than the high frequency slope. The lowest threshold for masking occurred when the frequency difference of the masking tone and a masked tone was small. The curves were wider from the low frequency end of the area than from the high frequency end. Contralateral masking was absent although a refractory period could be demonstrated by two consecutive ‘ p’ pulses. For a fixed frequency difference the intensity level of the masking tone or noise was a linear function of intensity level of the masked onset signal with a slope of one. A masking tone would cause the localized cortical response to an electrical shock delivered to a specific portion of the cochlea to vanish. Critical band width measurements with the onset of a tone for the masked signal and thermal noise for the masking signal were of the same general order of magnitude as the critical bands for human hearing. Certain similarities between the masking of the cortical responses and the general phenomenon of masking in human subjects were pointed out.
Role of the Splanchnic Nerve and the Adrenal Medulla in the Genesis of ‘Preoptic Pulmonary Edema’
Authors: Maire Frederick W. , Patton Harry D.
Published: December 2017

The pulmonary edema which follows preoptic lesions in rats is prevented by antecedent bilateral section of the splanchnic nerves. Intravenous epinephrine in doses exceeding 0.0125 mg/100 gm body weight causes fatal lung edema in rats comparable to that produced by preoptic lesions. Moreover, extracted pressor amines from rat adrenal glands cause lung edema, often fatal, when injected into the donor or into intact rats. However, adrenal demedullation does not prevent lung edema following preoptic lesions. Hence the protective effect of splanchnectomy against preoptic lesions is not wholly due to adrenal denervation. It is tentatively suggested that preoptic lung edema results from overloading of the pulmonary circuit owing to splanchnic mediated constriction of visceral venous reservoirs. Liver and spleen weights of animals dying from preoptic lung edema were significantly less than normal.
Glucose Oxidation by Normal and Virus-Infected Mice
Authors: Siegel Benjamin V. , Hughes Ann M.
Published: December 2017

The oxidation of uniformly labeled C14-glucose by normal mice and mice infected with strain MEF1 poliomyelitis virus was determined in an apparatus designed to measure respiratory radioactivity excretion. The respiration of normal and virus-infected mice was found to be essentially the same over a 10-day period of infection, although the production of virus in the diseased animal during this time was considerable. It is concluded that the rate and extent of viral multiplication in poliomyelitis is without apparent effect on the rate and extent of glucose metabolism by the infected intact host.
Metabolism of I131 by the Chronically Salivariectomized Rat
Authors: Watts Richard W. E.
Published: December 2017

The effect of chronic salivariectomy on the metabolism of a tracer dose of I131 has been investigated. Chronically salivariectomized rats excreted the isotope into the urine more slowly than intact rats and retained more of the injected material in the tissues. No significant differences were detected between chronically salivariectomized and intact rats from the point of view of the thyroid I131 content, or of the amounts of the isotope excreted in the feces. The possible role of the salivary glands in the metabolism of iodine and of the thyroid hormone is briefly discussed in the light of these findings.
Gastric Secretion Following Vagosplanchnic Nerve Anastomosis
Authors: Imparato Anthony M. , Reid L. Corsan , Hinton J. William
Published: December 2017

Gastric secretion in response to insulin hypoglycemia and electrical stimulation of the vagus was studied in 18 dogs who had bilateral vagosplanchnic anastomoses in the chest. In six dogs the pattern of gastric secretory response to insulin changed from negative in the early postoperative period to positive between 85 and 613 days postanastomosis. In two, apparent return of vagus function was confirmed by electrical stimulation of the vagi. One of five dogs in whom splanchnovagal nerve anastomoses were performed showed a return of response to insulin at 63 days which was abolished by excision of the anastomoses. On the basis of a review of some of the ideas regarding interpretation of cross nerve anastomoses and some of the conflicting opinions regarding the fiber content of the sympathetic splanchnic nerves, the authors conclude the most likely explanation for the observed phenomena is that there are preganglionic cholinergic fibers in the greater splanchnic nerves whose relationship to the gastric secretory apparatus is similar to that of cholinergic fibers in the vagus. The regenerating fibers of the vagus followed the sheaths of these degenerating fibers and re-established functional relationship with the gastric secretory apparatus.
Inhibitory Action of Bulbar and Suprabulbar Reticular Formation on the Spinal Reflex Pathway
Authors: Brooks Chandler McC. , Koizumi Kiyomi , Siebens Arthur A.
Published: December 2017

Inhibitory action of bulbar and suprabulbar reticular formation on spinal flexor and extensor reflex pathways was studied. In some instances a reciprocal effect was obtained but usually a generalized inhibition resulted. Inhibition varied in magnitude but was always present during reticular formation stimulation. In a high percentage of cases inhibition persisted for a period of 2–3 minutes after cessation of stimulation. Stimulations which blocked the reflex occasionally also had an inhibitory effect on the antidromic potential evoked by stimulation of the motor fibers involved in the reflex but in many instances the antidromic potential was actually augmented. The inhibitory stimulation also did not prevent facilitation of the antidromic potential by orthodromic stimuli. Post-tetanic potentiation was not prevented nor terminated by stimulation of the inhibitory areas of the reticular formation. This data suggest that inhibition from the reticular formation does not block afferent terminals but acts postsynaptically in such a manner, however, as not to increase axon hillock block of antidromic invasion of the soma. Effects of certain anesthetics and drugs on these phenomena were studied.
Metabolism of Isotopic Lactate by the Isolated Perfused Dog Gastrocnemius
Authors: Omachi Akira , Lifson Nathan
Published: December 2017

The metabolism of C13-lactate was studied in the isolated perfused dog gastrocnemius. Under the conditions employed, 12–13% of the respiratory CO2 was derived from the administered lactate (carboxyl-labeled) in unstimulated muscles, whereas 25–29% was so derived in muscle contracting at a rate of 2/sec. (from either carboxyl or α,ß-labeled lactate). Thus, the increase in the rate of conversion of lactate to CO2 associated with contraction was greater than the increase in the rate of CO2 production. Evidence for the conversion of administered lactate to glycogen was found only from the α,ß-labeled compound in unstimulated preparations given insulin and in the presence of moderate blood glucose levels. Such conversion was not demonstrated in any of the repetitively contracting muscles given carboxyl- or α,ß-labeled lactate or in unstimulated preparations administered carboxyl-labeled lactate.
Modification of Teratogenic Action of Cortisone in Mice by Maternal Age, Maternal Weight and Litter Size
Authors: Kalter Harold
Published: December 2017

Primigravid, hybrid female mice of a range of weights and ages were given injections of 2.5 mg cortisone acetate/day for 4 successive days beginning 11 1/3 days postconception. The frequency of offspring born with median cleft palate decreased with increasing maternal weight, advancing maternal age and increased litter sizes. Analysis of the data by multiple regression has shown that the cleft palate frequency depends on maternal weight, and that maternal age and litter size seem to play a role only because they are so highly correlated with maternal weight. In mice of constant parity, therefore, heavier animals are more resistant to the cleft palate-inducing properties of cortisone than lighter animals are. The possible role of maternal fat metabolism is discussed.
Effect of Concentration of KI and of Temperature on Shortening of Glycerol-Treated Muscle Fibers in KI Solutions
Authors: Bowen W. J. , Laki K.
Published: December 2017

Experiments reported here further support the previous conclusion that the shortening of glycerol-treated muscle caused by neutral Nessler's reagent (HgI2 in KI solution) is essentially due to the KI component. Analysis of the data obtained indicates that the apparent binding constant of KI to the contractile protein is 5 or 6 m/l. The same value for the binding ATP is about 10,000. The extent and speed of shortening in HgI2-KI solution are temperature dependent. The molecular rearrangement which results in the shortening of glycerol-treated fibers is considered to be directly related to the binding KI to the protein.
Continuous C14O2 and CO2 Excretion Studies in Experimental Animals
Authors: Tolbert B. M. , Kirk Martha , Baker E. M.
Published: December 2017

An apparatus has been devised which permits, after administration of labeled compounds to animals, the continuous measurement and recording of CO2 excretion by means of infrared absorption, C14 excretion by ion chambers, and specific activity by a ratio analyzer. Comparative excretion studies have been made using labeled amino acids, fats, fatty acids and sugars. The specific activity and total activity rate curves for breath carbon-14 are markedly different. The generally smooth nature of the specific activity curves gives an excellent indication of the continuous and steady processes by which radioactivity is distributed into the various body pools. Studies have been made with mice, rats, guinea pigs and rabbits. As small an amount as 0.1 µc C14 has been used for an 8-hour study in mice. The instrument can be readily adapted for use in large animal or human studies following administration of small amounts of C14.
Renal Extraction of PAH and of Diodrast-I131 as a Function of Arterial Red Cell Concentration
Authors: Kinter W. B. , Pappenheimer J. R.
Published: December 2017

The cell separation theory of renal hemodynamics predicts that the renal extraction of substances secreted by the tubules should vary with the concentration of red cells in arterial blood. This prediction has been tested in anesthetized cats and dogs breathing oxygen. The renal extractions of PAH and of trace concentrations of Diodrast-I131 were found to be smooth and reversible functions of the arterial red cell concentration. The transfer maxima of these substances were unaffected by removal of red cells and the extraction ratios decreased as a function of arterial hematocrit ratio even when the renal plasma flow was maintained constant. The results indicate that at low red cell concentrations about 50% of the renal plasma flow bypasses the tubular elements of the kidney. According to the cell separation theory this extra-tubular flow of plasma takes place through a short circulation which normally contains a cell-rich moiety of the blood.
Effects of Intravenous Infusion of Carbonic Anhydrase on Carbon Dioxide Tension of Alkaline Urine
Authors: Ochwadt Bruno K. , Pitts Robert F.
Published: December 2017

Five dogs were rendered hydropenic by withholding water for 20 hours and mildly alkalotic by the infusion of sodium bicarbonate intravenously in small amounts. Under these conditions alkaline urine was formed at approximately 1.0 cc/min. In 15 control periods the pCO2 of the urine exceeded that of the plasma, the ratio averaged 2.08 ± 0.44 (S.D.) with a range of 1.45–2.79. Following the intravenous administration of 100 mg of carbonic anhydrase as a priming dose and the infusion of the enzyme at a rate of 1 mg/min., the ratio in 25 experimental periods decreased to an average of 0.988 ± 0.14 (S.D.) with a range of 0.78–1.30. We conclude that the high carbon dioxide tensions commonly observed in alkaline urines result from delayed dehydration of carbonic acid to carbon dioxide in the renal tubule.
Role of Oxygen and Exogenous Glucose and Lactic Acid in the Performance of the Heart
Authors: Alella A. , Williams F. L. , Bolene-Williams C. , Katz L. N.
Published: December 2017

The relationship (over the normal range) between work, the consumption of oxygen, glucose and lactic acid and the RQ have been studied on the heart in situ in controlled experiments. The following conclusions were reached: a) The correlation found between work and oxygen consumption was imperfect because the behavior of a heart when its work is increased is different as regards oxygen consumption when it is performing pressure-work than when it is performing an equal amount of volume-work. b) The heart rate is an important factor in determining the oxygen consumed by the heart in situ at a given work load. c) The RQ was found to be unrelated to the work level of the heart. It remained relatively constant over the normal range indicating that the nature of the metabolism is probably not altered. d) A low value of ‘efficiency’ was found in this preparation. It does not necessarily indicate an incompetent or insufficient heart. The biological significance of the term, ‘efficiency’ which actually represents merely the ratio of work done to the amount of oxygen consumed, is considered. e) The availability of glucose and lactic acid is not dependent upon the work of the heart; their availability is dependent upon the coronary flow and therefore varies with oxygen consumption. f) The consumption of exogenous glucose by the heart is related to the availability of glucose but not to its arterial blood level. The exogenous glucose consumption of the heart is not related to the cardiac oxygen consumption. g) The consumption of exogenous lactic acid by the heart shows a positive relation to its availability, to its arterial blood level and to the myocardial consumption of oxygen. It appears to be one of the substrates readily used for the work performance of the heart. h) The relative consumption of exogenous glucose and lactic acid by the heart varies with their relative availabilities. i) The significance of these findings is discussed.
Effect of Chlorpromazine on Survival From Hemorrhagic Shock
Authors: Spurr G. B. , Farrand Enid Allbaugh , Horvath Steven M.
Published: December 2017

In dogs subjected to a standard procedure of irreversible hemorrhagic shock, a 2-mg/kg dose of chlorpromazine administered 30 minutes previous to the hemorrhage has been found to exert a protective action in terms of survival. No beneficial action of the chlorpromazine was evident when this dosage of the drug was given 5 hours prior to or immediately after the initial hemorrhage. When chlorpromazine was administered in a dose of 5 mg/kg 30 minutes before the onset of bleeding the survival frequency was not significantly different from that observed in the control animals. While the mechanism of the protective action of chlorpromazine in hemorrhagic shock has not been revealed by these studies, the results indicate that it is not primarily a function of the autonomic blocking properties of the drug. Neither is it related directly to the smaller hemorrhage required to induce a standard level of hemorrhagic hypotension.
Effect of Various Amino Acids on the Renal Tubular Reabsorption of Inorganic Sulfate in the Dog
Authors: Berglund Fredrik , Lotspeich William D.
Published: December 2017

Various amino acids depress the sulfate-Tm in the dog. The effects of l-alanine, glycine, d-alanine and l-arginine are compared. The capacity of any one of these amino acids to depress sulfate-Tm correlates directly with maximal rate of reabsorption of the amino acid. The nature of the amino acid inhibition, its relation to amino acid reabsorption, the amino-acidurias and some general problems of renal tubular reabsorption are discussed.
Comparison of Blood Flow in Normally Innervated and in Sympathectomized Legs of Dogs After Exposure to Cold
Authors: Imig C. J. , Roberson W. J. , Hines H. M.
Published: December 2017

Volume blood flow was measured by a technique of venous occlusion plethysmography in hind legs of dogs with intact innervation and in sympathectomized legs during and following rewarming after exposure to cold. The area of the leg from the level of the knee down was immersed in an alcohol dry-ice mixture at –4°C for 3 1/2 hours. During and for some time after rewarming there occurred an increase in blood flow in exposed hind legs with intact innervation but no change occurred in sympathectomized legs after their exposure to cold. These findings point to some type of vasomotor dysfunction or impairment as being responsible for the increase in blood flow in normally innervated legs following their exposure to cold.
Reduction in Pancreatic Proteinase After Hypophysectomy
Authors: Baker Burton L. , Reid Norma L. , Thoms Nancy
Published: December 2017

Proteinase activity was determined in the pancreas of hypophysectomized and nonhypophysectomized rats. Following activiation with enterokinase, pancreatic homogenates were digested with a hemoglobin substrate and activity ascertained colorimetrically in terms of tyrosine released. When calculated on the basis of activity per gram of pancreas, total activity or total activity in relation to body weight, the values were significantly lower in hypophysectomized as contrasted to nonhypophysectomized rats.
Biochemical Response to Trauma
Authors: Young James G. , Gray Irving
Published: December 2017

The effect of tumbling trauma on the concentration of epinephrine and norepinephrine in the plasma of rats has been followed using the fluorimetric method of Weil-Malherbe and Bone for the analysis of the catechol amines. Sprague-Dawley rats weighing 250 gm were used. The animals were tumbled for 300, 400, 500, 600, 700 turns giving a 24-hour mortality ranging from 0–100%. The epinephrine levels immediately after the tumbling were increased 2–5 times while the norepinephrine concentrations increased 5–10 times. When followed in time after tumbling, the epinephrine remained elevated for 1–2 hours and returned to normal within 4–8 hours, while the norepinephrine began to fall within 1 hour and had returned to normal within 4–8 hours. Although changed excretion is ruled out, the actual role of secretion and biotransformation cannot be ascertained.
Effect of Intravenous Injection of Hypertonic Glucose Solution on External Secretion of the Pancreas
Authors: Crider J. O. , Conly S. S. , Dorchester J. E. C. , Thomas J. E.
Published: December 2017

Effect of the intravenous administration of hypertonic glucose solution on the specific gravity, volume and amylase content of pancreatic juice collected from unanesthetized, chronic fistula dogs secreting in response to hydrochloric acid in the duodenum was studied. There was an increase in the specific gravity and amylase but no change in volume.
Effect of Streptokinase on Mustard Oil Inflammation of the Rabbit Eye
Authors: Gordon Samuel , Ablondi Frank B. , Cekleniak Walter , Hutchings B. L.
Published: December 2017

Intravenous or intramuscular streptokinase (SK), 100,000 or 500,000 u, respectively, was administered prior to the instillation of mustard oil in the rabbit eye. Comparison of the SK-treated animals with saline controls indicated that SK was effective in reducing this type of experimental inflammation.
Positive Chronotropic Effect of Increasing Right Atrial Pressure in the Isolated Mammalian Heart
Authors: Blinks John R.
Published: December 2017

Effect of increasing right atrial pressure on the rate of the mammalian heart was studied in the isolated dog heart and in an isolated atrium preparation of the rabbit. It was shown that increases in right atrial pressure may increase the heart rate by more than 50%. The rabbit atrium is sensitive to a rise in pressure from 0 to 25 mm of water; a maximal rate response can be elicited by a pressure of about 100 mm of water. Local anesthetics in nontoxic concentrations, tetraethylammonium ion, and veratramine have no consistent effect upon the pressure response. It is suggested that mechanical tension may exert a direct stimulatory influence upon pacemaker tissues in general.
Role of the Spleen in Acclimatization to Hypoxia
Authors: Cook S. F. , Alafi M. H.
Published: December 2017

In order to determine quantitatively the participation of the spleen and the bone marrow separately, five groups of splenectomized and non-splenectomized mice totalling 87 individuals were exposed to a simulated altitude of 15,000 feet continuously for periods of 30–58 days. RBC counts and hematocrit determinations were made at various intervals. It was found that about two-fifths of the increase in red cells could be referred to a tonic contraction of the spleen and the remaining three-fifths to the production of red cells by the bone marrow.
Excretion of Radioactive Zinc (Zn65) in Bile, Pancreatic and Duodenal Secretions of the Dog
Authors: Birnstingl Martin , Stone Bernard , Richards Victor
Published: December 2017

There is more Zn65 secreted per cubic centimeter of sample, and per volume collected in pure pancreatic juice than in bile or duodenal secretions. The increased radioactivity of pancreatic juice appears earlier, reaches a higher peak, and lasts longer than corresponding collections of bile or duodenal juice as periodically measured during the first 6 hours following intravenous injection of radioactive zinc (Zn65). Ligation of the pancreatic ducts materially decreases the radioactivity of otherwise intact duodenal aspirate.
Influence of Androgens on Transaminase Activities of Different Tissues
Authors: Kochakian Charles D. , Endahl Barbara R.
Published: December 2017

Male guinea pigs (Hartley) were castrated at 510 (450–580) gm body weight and 30 days later were implanted subcutaneously with pellets of 12 different androgens. After 21 days of treatment the temporal muscles showed an increase in aspartic-glutamic and alanine-glutamic transaminase activities in proportion to the increase in the weight of the muscles. The kidney, heart and liver showed no changes in weight or activity of the enzymes as a result of treatment with the androgens.
Factors Influencing Alveolar-Arterial Oxygen Pressure Gradient
Authors: Atwell Robert J. , Tomashefski Joseph F. , Ryan Joseph M.
Published: December 2017

The A-a oxygen pressure gradient was determined in anesthetized dogs. Data obtained when pulmonary ventilation and alveolar oxygen tension are varied independently suggests that: a) the magnitude of the A-a oxygen pressure gradient correlates directly with the Paoo2. b) In the anesthetized dog venous admixture seems to be constant, unrelated to the changes in ventilation produced by positive-negative pressure breathing. c) Venous admixture is the most important factor in producing the A-a gradient in the dog.
Glycogenolysis in the Anoxic Heart
Authors: Bloom Walter L.
Published: December 2017

It has been generally accepted that cardiac anoxia caused glycogen depletion and epinephrine was implicated as a mediator in this glycogenolysis. Recently, work has shown that epinephrine and norepinephrine produce an increase in cardiac glycogen rather than glycogen depletion in the rat. Since cardiac work was not considered in previous studies, the present experiment was designed to test the effect of work on glycogenolysis of the anoxic heart in vivo and in vitro. Unfasted rats were anesthetized and observations were made on intact rats with anoxia resulting from an open chest. In vitro studies were performed on rapidly excised hearts studied in room air, in saline and in nitrogen. After 4 minutes of anoxia in the open chest 83% of the control glycogen was lost and no difference was noted whether or not the adrenal medullae were present. When the large vessels were severed, much less glycogenolysis occurred in the anoxic heart. No glycogen decrease was observed in the excised heart beating 4 minutes in room air or in nitrogen, but significant glycogenolysis was observed in the anoxic heart beating 4 minutes in saline. The anoxic heart severed from the circulation has shown no glycogenolysis whereas the anoxic heart with intact circulation showed marked glycogenolysis. It would appear from this experiment that anoxia per se was not the cause of glycogen decrease but that the amount of work performed by the anoxic heart was the critical factor in producing glycogenolysis. When a work load was placed on the excised heart beating in saline, glycogen decrease was observed. Epinephrine has been excluded as the cause of glycogenolysis in the anoxic heart since comparable cardiac glycogen changes were observed during anoxia in normal and adrenal demedullated rats.
Cardiovascular Effects of Chlorpromazine in the Dog
Authors: Spurr G. B. , Horvath Steven M. , Farrand Enid Allbaugh
Published: December 2017

Chlorpromazine in doses of 2 and 5 mg/kg has been found to produce an initial hypotension in anesthetized dogs which was followed by return of the mean arterial blood pressure to near control levels. During the next 60–65 minutes there was a secondary decline in the pressure to hypotensive levels. Both an initial and secondary hypotension were the result of a decrease in peripheral vascular resistance.
Neurohypophyseal Responsiveness in the Hypertensive Rat
Authors: Friedman Sydney M. , Hinke J. A. M. , Friedman Constance L.
Published: December 2017

Neurohypophyseal responsiveness in normotensive and hypertensive rats was studied using a standardized intracarotid injection of a sodium chloride solution as osmotic stimulus. The response was judged by measuring the rate of urine flow before and after stimulation. Rats under DCA treatment for 3 or 6 months, as well as rats with permanent post-DCA hypertension or with spontaneous senescent hypertension were used in four separate experiments. All experiments showed the neurohypophysis of the hypertensive groups to be more responsive than its control. This is interpreted to mean that the secretion of antidiuretic hormone is inhibited and tends to accumulate in hypertension.
Effects of Intravenous Administration of Fat Emulsion on Formed Blood Elements and Body Temperature in Dogs
Authors: Meng H. C. , Cress Hertha , Youmans John B.
Published: December 2017

Intravenous administration of a 10% olive oil emulsion or lymph to healthy dogs anesthetized with Nembutal produced marked thrombocytopenia, leucopenia, neutropenia, eosinopenia, lymphopenia, increase in mechanical fragility of erythrocytes, and increase in hematocrit. The increase in mechanical fragility of erythrocytes correlated directly with the degree of lipemia. Heparin administration accelerated the removal of the injected fat from the circulation and hastened the return to normal of the formed blood elements. The changes in the formed blood elements were more marked and persisted longer in the dogs receiving piromen. The changes in the formed blood elements following oral ingestion of olive oil were either mild or insignificant except for the moderate eosinophilia. Elevation of rectal temperature and persistent lymphopenia were observed only in the animals receiving emulsion and piromen. It is concluded that the changes in formed blood elements, including the increase in mechanical fragility of erythrocytes following intravenous administration of fat emulsion, did not seem to correlate with the rise of body temperature.
Dependence of Intracellular End-Plate Action Potential on Adjacent Fiber Activity
Authors: Easton Dexter M.
Published: December 2017

Intracellular action potentials were recorded at the end plate and 1 mm away from it in small bundles of m. adductor longus of Rana pipiens during stimulation of the nerve. The end-plate spike reached a lower maximum and the repolarization was slower when compared with the spikes recorded 1 mm away. The difference was of the form expected from externally recorded impulses, and was much diminished when the number of fibers was reduced to two to three. It is suggested that asynchrony of the activity in adjacent fibers explains the lesser distortion of action potentials distant from the end plate.