bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Ca/P ratio and pH on calcium and phosphorus absorption from dog gut loops in vivo
Authors: Cramer Carl F.
Published: April 2011

The effect of Ca/P ratios and pH on absorption of Ca and P was measured in vivo in dogs with healed intestinal loops. With Ca constant, variations either of P/Ca or pH did not alter Ca absorption. With no phosphorus, Ca absorption was significantly depressed. Phosphorus absorption was proportional to phosphorus concentration in this perfusate, and was depressed by a lowered pH. With a high Ca concentration, percentage Ca absorbed rose, and was unaffected by P/Ca ratio or pH. It was concluded that P/Ca ratios and pH are not important as factors which limit calcium or phosphorus absorption, in vivo, within reasonable physiologic dietary concentrations of these elements.
The cardiovascular system and renal control of sodium excretion
Authors: Mills Ivor H.
Published: April 2011

Sodium diuresis can be produced by saline infusion when the glomerular filtration rate (GFR) is reduced by aortic constriction. Renal vasodilators produce a rise in sodium excretion in excess of what can be explained by changes in GFR. Raising intrarenal pressure by transient intermittent renal vein occlusion causes a sodium diuresis. These studies suggest that there is a pressure-sensitive site in the kidney which can influence sodium excretion. This has been confirmed with a perfused isolated kidney in which it has been shown that sodium excretion is increased by raising the perfusion pressure or lowering the hematocrit. Patients with postural hypotension produce a sodium diuresis on lying down even at night and a dramatic rise in sodium excretion with blood transfusion even when the jugular venous pressure rises. The pressure getting through the afferent arteriole probably triggers this off. This is because loss of control of the tone on the afferent arteriole makes the region of the juxtaglomerular cells sensitive only to changes in blood pressure. Graded carotid artery constriction in dogs causes first sodium retention and later sodium diuresis. On the other hand, raising blood pressure by increasing the cerebrospinal fluid pressure causes sodium diuresis initially and later sodium retention. It is suggested that these opposite effects on sodium excretion associated with different methods of raising blood pressure may be explained by the regulation of renal arteriolar tone independently of the blood pressure and of the tone on other parts of the vasculature.
Storage and secretion of neurohypophyseal hormones
Authors: LaBella Frank S.
Published: April 2011

Investigations in the author's laboratory which bear upon several fundamental aspects of the mammalian neurohypophysis were reviewed and related to well-established or currently accepted concepts, (a) The separation of vasopressin-rich from oxytocin-rich neurosecretory granules (NSG) from posterior pituitary homogenates was achieved. (b) The hormone and amino acid composition of isolated NSG was found to be almost identical to that of the van Dyke protein, prepared by chemical extraction of posterior pituitary glands, indicating that the protein is synonymous with the NSG carrier protein to which vasopressin (VP) and oxytocin (OT) are bound. (c) Pinched-off nerve terminals (neurosecretosomes) were isolated from homogenates by centrifugation and shown to be metabolically and morphologically intact. The hexosemonophosphate shunt was highly active in the nerve terminals, where the peptide hormones are stored and secreted, but not in the cell bodies within hypothalamic nuclei, where they are synthesized. (d) Neurosecretosomes relatively enriched in VP were separated from those rich in OT by density-gradient centrifugation, providing support for the concept that a given neurohypophyseal neuron stores and secretes only one of the hormones. (e) Electron microscopy indicated that microvesicles, about 50 mμ in diameter, and called "synaptic" vesicles by some workers, are derived from membranes of depleted NSG and are not of the type that contain neurotransmitter. (f) Acetylcholine (ACh), choline acetyltransferase, and acetylcholinesterase were identified in the posterior pituitary gland and are present in about the same proportions but 1/5 to 1/10 the activity as in whole brain. ACh was found in the neurosecretosome and microvesicle centrifugation fractions. The three cholinergic components in the posterior pituitary are believed to be constituents, not of neurosecretory nerve endings which contain VP or OT, but of specific cholinergic neurons whose role in neurohypophyseal physiology remains to be elucidated. (g) VP and OT are generally released together from the gland in vivo and from posterior pituitary tissue or NSG in vitro. However, exceptions can occur both in vivo and in vitro in which one of the hormones is apparently released exclusively. Studies on the release of VP and OT in vitro show that the NSG–hormone complex is more labile in the case of OT than of VP, an observation that suggests a molecular basis for numerous in vivo findings in which a preponderance of OT over VP is secreted in response to a wide variety of stimuli.
Glycogen content of mouse hemidiaphragm as a biologic indicator of insulin action
Authors: Davidson J. K. , Coddling Judith A. , Haist R. E.
Published: April 2011

The mouse hemidiaphragm insulin assay utilizes glycogen content as the biologic indicator of insulin activity. It is statistically valid and has a mean index of precision of 0.22. The effects of alterations in the incubation medium showed that hyperosmolarity, hypo-osmolarity, and inadequate oxygenation reduced the glycogen content. There was a linear increase in glycogen content when it was plotted against the log of glucose concentration from 3 to 20 mg/ml. At these glucose concentrations, maximal insulin stimulation increased glycogen content 50–100%. Optimal pH was 7.34–7.53 and optimal incubation time was 90 min. Insulin activity of native serum (NSIA) was low in peripheral vein and much higher in pancreatic vein. Insulin activity in acid alcoholic treated dialyzed serum (TSIA) was much higher than NSIA in peripheral vein and significantly higher in pancreatic vein. NSIA was neutralizable; the additional activity made manifest by treatment was not. The effect of NSIA, TSIA, and standard insulin decreased in parallel manner with dilution.
Matched rates of insulin infusion and secretion and concurrent tracer-determined rates of glucose appearance and disappearance in fasting dogs
Authors: Vranic M. , Wrenshall G. A.
Published: April 2011

The endogenous secretion rate of insulin in the dog was matched by an intraportal infusion of exogenous pork insulin at a rate of 12 milliunits/kg h following removal of the remnant pancreatic autograft. Both homeostasis and a dynamic steady state for glucose were observed. An apparent functional relationship between the infusion rates of insulin (7.2–16.4 milliunits/kg h) and the tracer-determined rates of glucose appearance and disappearance was found following graft removal, but not in the diabetic dog after reduction of hyperglycemia. With rates of insulin infusion less than 12 milliunits/kg h the rate of glucose appearance increased and the rate of its disappearance decreased, causing glucose accumulation. Opposite changes were observed with insulin infusion rates from 15 to 156 milliunits/kg h. When the infusion was switched from the portal to a nonsplanchnic vein the dog was more sensitive to the hypoglycemic action of insulin. The switch-off of insulin infusions, maintained for 4.5–7.0 h in the depancreatized dog at different glucose levels, resulted within 2 min in a rise in plasma glucose concentration caused by both underutilization and overproduction of glucose. Overproduction of glucose was still observed 15 h thereafter, when a new steady state was being approached. It is postulated that in the fasting dog at normal glucose levels a continuous insulin secretion of 12 milliunits/kg h is indispensable for the apparent negative feedback mechanism to maintain glucose near the dynamic steady state. In the absence of insulin, the apparent feedback mechanism becomes functional again but at high glucose levels.
Adaptive changes in rates of appearance and disappearance of glucose in dogs following step changes in the rate of glucose infusion
Authors: Hetenyi Jr. G. , Wrenshall G. A.
Published: April 2011

The intravenous infusion of glucose at rates corresponding to 17–79% of the endogenous (hepatic) rate of glucose production decreased the latter in both normal and diabetic dogs. The increase in the rate of the exogenous infusion and the decrease in the rate of endogenous production were found to be positively correlated. The correlation between the change in the rate of glucose disappearance (utilization plus excretion) and the change in the rate of the exogenous infusion was significant in normal but not in diabetic dogs. The infusion of galactose had no effect on endogenous glucose production. Infusions into the cephalic vein or into the carotid artery were equally effective in decreasing endogenous glucose production. It appears that the rate of endogenous (hepatic) glucose production adapts to an exogenous glucose infusion in both normal and diabetic dogs. Such an adaptation in the rate of glucose disappearance (disposal) was observed only in normal but not in pancreatectomized dogs. Thus the role of the release of insulin in such adaptation is to increase the disposal rather than to decrease the rate of the endogenous production of glucose. The specificity of the adaptive mechanism is demonstrated by the ineffectiveness of galactose in altering glucose turnover.
The effects of hypothermia and insulin on the distribution of glucose in some tissues of the rat
Authors: Henderson Margaret J. , Haag Ann L. , Haist R. E.
Published: April 2011

In fasted hypothermic rats (25 °C), after a glucose load of 1 g/kg body weight, in either the presence or absence of injected insulin (0.5 units/kg), the rate of disappearance of glucose from the blood was decreased as compared with that of normothermic rats (37 °C). Hypothermia did not change the total water content of diaphragm, rectus abdominis muscle, heart, or liver of these rats, nor did it change the sodium space of these tissues. Insulin-injected hypothermic rats did show an increase in the sodium space of the diaphragm. The glucose space of the muscle tissues was not changed by hypothermia, but was greatly increased by insulin in both hypothermic and normothermic rats. The glucose space of the liver was increased by insulin in normothermic rats, but in hypothermic rats an increase was found only when larger quantitites of insulin were injected. Intracellular glucose could not be detected in the diaphragm, rectus abdominis muscle, or heart of either normothermic or hypothermic rats in the absence of injected insulin, but was present in the liver of both. The injection of insulin caused intracellular glucose to accumulate in the diaphragm and heart of both normothermic and hypothermic rats. The level was increased by hypothermia only in the heart, suggesting that in this tissue the intracellular metabolism of glucose was decreased.
The effects of propylthiouracil, thyroxine, and hypophysectomy on the iodinating activity of the rat thyroid gland
Authors: Zimmerman A. E. , Yip C. C.
Published: April 2011

The effects of increasing or decreasing the endogenous secretion of thyroid-stimulating hormone on the iodinating activity of the rat thyroid gland were investigated. The thyroid iodinating activity of rats on 0.01% propylthiouracil in the drinking water increased linearly for 3 days and reached a maximum of 230 to 240% of the control on or about the fourth day of treatment. The daily injection of thyroxine (10 μg/100 g intraperitoneally) or hypophysectomy resulted in a rapid decrease in the iodinating activity between the first and second day, approaching a basal level by the third day. When the iodinating activity was suppressed for 4 days by daily injections of thyroxine, the activity began to rise on the fifth day after termination of thyroxine treatment.
Characteristics of nucleotide-converting enzymes at muscle surfaces with special reference to ion sensitivity
Authors: Manery J. F. , Riordan J. R. , Dryden E. E.
Published: April 2011

Spectral analyses in the ultraviolet range, paper chromatography, and determinations of the release of inorganic phosphate were used to extend the investigation of the surface enzymes (frog muscle) which catalyze the conversion of ATP→ADP→AMP→IMP. ATPase and 5′-AMP deaminase appear to adhere firmly to the muscle cell surface, even after three successive incubation periods of 4 h each, whereas the adenylate kinase is more loosely bound. The observed loss of the activity of the complete enzyme system with time was shown to be due to a suboptimal substrate concentration and not to the accumulation of products of the reaction. The AMP deaminase activity was inhibited if sodium and potassium chloride were replaced by choline chloride in the incubation media. Cation analyses of media and the determination in muscle of Na, K, water, and the sorbitol-14C space permitted a calculation of the actual intra- and extra-cellular cation concentrations. In choline-containing media the intracellular potassium was in part replaced by choline. The data indicated that the deaminase was influenced by the external, not the internal, cation concentrations. Magnesium ions stimulated the inorganic phosphate release catalyzed by ATPase and adenylate kinase but inhibited the AMP deaminase. Intact frog muscle also converted GTP, CTP, UTP, and ITP in the medium to the corresponding nucleoside monophosphate.
Effects of beta-adrenergic blockade on the heart rate and energy expenditure of sheep during feeding and during acute cold exposure
Authors: Webster A. J. F. , Hays F. L.
Published: April 2011

Heart rates, respiratory exchange, and rectal temperatures of five sheep were measured during 4 h exposure to −30 °C and during a 3-h period at +8 °C in which the sheep fed for 1 h. Propranolol, a beta-adrenergic receptor blocking agent, was infused at 0.25, 0.5, and 1.0 mg/kg in both series of experiments. These doses blocked isoproterenol-induced tachycardia. Exposure of the untreated sheep to −30 °C produced marked increases in both energy expenditure and heart rate. Propranolol infusion at 0.25 and 0.5 mg/kg had no effect on energy expenditure but almost totally abolished cardioacceleration in response to cold. Propranolol at 1.0 mg/kg significantly reduced energy expenditure at −30 °C. Both heart rate and energy expenditure increased markedly in the untreated sheep during feeding. Propranolol at 0.25, 0.5, and 1.0 mg/kg had significantly similar effects on heart rate during feeding, reducing the absolute values attained at only 12%. Cardioacceleration during feeding was, however, reduced by 46% because propranolol infusion increased heart rate in the prefeeding period. Propranolol at 0.5 mg/kg had no effect on energy expenditure during feeding. It was concluded that the sympathetic system, acting through the beta receptors, is of major importance in controlling the metabolic and cardiac responses of sheep to acute cold exposure, but of minor importance in initiating and regulating these responses during feeding.
Energy and water requirements in the house mouse (Mus musculus)
Authors: Wood A. J. , Nishimura T.
Published: April 2011

The mature mouse has been shown to consume both feed and water at levels that are compatible with predictions that can be made from work with other species. The apparent digestible energy intake (A.D.E., kilocalories) was related to body weight (W, kilograms) by the equation A.D.E. = 148.7 W0.71, and the total water requirement (WA, grams) by the equation WA = 91.9 W0.73. The total water requirement increased by 0.605 g per kg-cal of apparent digestible energy ingested, WA = 0.222 + 0.605 A.D.E. An inexpensive apparatus for the measurement of feed and water intake and urine and fecal collection is described.
Experimental immune hemolytic anemia and blood sugar levels
Authors: Adamkiewicz V. W. , Skanes V. M. , Sacra P. J.
Published: April 2011

Injection of rabbit antimouse erythrocyte serum into mice results in a complex hemolytic anemia syndrome with erythropenia, splenomegaly, a terminal decrease in blood sugar levels, and death. The intensity of the syndrome while being directly proportional to the antiserum dose is inversely proportional to blood sugar levels at the time of inoculation; thus, within certain limits, the hyperglycemic state partially neutralizes the toxicity of the antiserum.
Animal respiratory mask
Authors: Routledge F. G. , Topliff E. D. L. , Livingstone S. D.
Published: April 2011

An animal respiratory mask is described which provides a leak-proof facial seal by reason of a pneumatic moulding to facial contours. The mask is shown to be versatile with respect to size and shape of the animal's face.
Power spectral density and probability analysis of electromyograms in shivering birds
Authors: West George C. , Funke Edgar R. R. , Hart J. Sanford
Published: April 2011

The spectral analysis of electromyograms from evening grosbeaks, Hesperiphona vespertina, and common grackles, Quiscalus quiscula, revealed a statistically significant higher upper cut-off frequency during shivering in the former species. There was also a statistically significant decrease in the upper cut-off frequency with lowering of temperature in the evening grosbeak, but not in the grackle. The frequency of occurrence of various amplitudes during shivering followed the normal distribution closely in both species. The presence of frequencies in the range from 6 to 600 c.p.s. necessitates the use of wideband instrumentation for fidelity in measuring species differences.
A method for the study of mechanisms of drug disposition in smooth muscle
Authors: Kalsner Stanley , Nickerson Mark
Published: April 2011

Observations on rates of dissipation of responses to various agonists, protection of receptors by residual agonist after washout, and effects of enzyme inhibitors on these processes established that relaxation of rabbit aortic strips is controlled by the concentration of agonist remaining in the environment of tissue receptors. Thus, the rate of relaxation is a valid index of overall drug inactivation. This index of drug disposition was combined with a procedure of oil immersion, which traps a fixed amount of drug in an extracellular compartment only slightly larger than the interstitial space of the tissue. Oil immersion did not detectably alter the functional capacity of the tissue and effectively separated intrinsic disposition from diffusion into the external medium. Examples are given to show that, in combination with inhibitors of specific pathways of disposition, this preparation provides a simple, quantitative, reproducible method for the study of mechanisms of drug inactivation, with the advantages that it (a) allows the study of responses and disposition in the same preparation, (b) allows analysis of the inactivation of any concentration of agonist which produces a recordable response, (c) equates disposition with termination of action, and (d) specifically follows effective drug in the environment of receptors rather than total drug in the tissue.
A comparison of the efflux rates of AIB from kidney cortex slices of mature and newborn rats
Authors: Webber W. A.
Published: April 2011

Earlier observations of the pattern of uptake of amino acids by rat kidney cortex slices taken from mature and from newborn animals indicated that although the initial rate of entry was invariably more rapid in the mature tissue, the concentration gradient eventually achieved was consistently higher in the newborn tissues. Assuming that the rate of entry was relatively constant, the final concentration differences could only be explained if there was a significantly more rapid efflux of amino acid from the mature tissues. Studies were therefore carried out to measure the rate of efflux of 14C-labelled α-aminoisobutyric acid (AIB) from newborn and mature tissues previously loaded with this nonmetabolized amino acid. It was observed that the rate of efflux was markedly greater in the case of the mature tissues. At 1 h the proportion of AIB which had effluxed was about twice as great in the mature as compared with the newborn tissue. A comparatively small fraction of the efflux from both types of tissue was shown to be dependent on the concentration of external AIB and may have resulted from an exchange diffusion process. This fraction did not account for any significant part of the difference in efflux rates, which probably was the result of different rates of passive diffusion.
The initial uptake of copper by the liver in the dog
Authors: Goresky Carl A. , Holmes Thomas H. , Sass-Kortsak Andrew
Published: April 2011

The initial uptake of 64Cu and serum and tissue copper levels were examined in the dog. Plasma disappearance curves, multiple indicator dilution studies of initial hepatic uptake, and constant infusion experiments were carried out, at various doses, before and after preloading with cupric acetate. Over a range of plasma concentrations of direct-reacting copper extending to levels far above those encountered under physiological circumstances, little evidence of saturation of the initial hepatic uptake was evident. The countertransport of labeled copper was produced by administering unlabeled copper. The tissue levels of copper in the liver of the normal dog were, unexpectedly, found to be comparatively high, to average 82 μg/g wet weight. Attempts to produce manyfold increases in this copper content by daily intravenous copper administration failed because the doses of copper which would have been necessary to produce the increases, doses which would not have caused major toxic effects in the rat, were lethal for the dog. This low tolerance for copper loading presumably reflects the preexisting high copper concentration in the liver, the major organ which takes up exogenously administered copper. The degree of preloading which could be achieved produced no perceptible change in initial hepatic uptake. The copper levels in the liver are of the order of those found in some patients with Wilson's disease. Despite this, none of the other abnormalities which characterize this disease have been encountered in dogs.
Water and electrolyte exchange in rats exposed to cold
Authors: Fregly Melvin J.
Published: April 2011

Exposure of rats to air at 6 °C for 10 days increased food intake and urine output but failed to affect water intake. A comparison of water with food intake revealed a smaller water intake for a given food intake for cold-exposed than for control rats. The urine output at a given water intake was also greater for cold-exposed rats. In addition, cold exposure failed to affect urine osmolality significantly. Thus, the greater solute output accompanying cold exposure was accomplished by increasing urine flow rather than by concentrating urine. These results suggest possible mechanisms for both the relative dehydration and increased plasma osmolality observed after removal of rats from cold air. Both fecal and urinary routes of sodium and potassium excretion were increased by cold exposure; however, fecal excretions of both potassium and sodium were greater fractions of the total output during cold exposure than prior to it. Although cold exposure tends to induce a relative dehydration in rats, an important factor limiting the extent of the dehydration may be increased fecal electrolyte loss.
The effect of adrenal demedullation on the blood sugar level of rats subjected to long-term cold stress
Authors: Jarratt Alison M. , Nowell N. W.
Published: April 2011

Blood sugar levels and adrenal weights (where possible) were recorded, after a 24-h fast, in normal intact, adrenal-demedullated, and adrenalectomized rats kept at 4 °C for up to 130 days. These were compared with data from control rats kept at 21 °C. Hypoglycemia (relative to the control value) prevailed in both normal intact and, more profoundly, in adrenal-demedullated rats during the first 24 h of chilling but no deaths occurred. Adrenalectomized rats, whose blood sugar level at 21 °C was subnormal, at 4 °C soon showed extreme hypoglycemia and died. More prolonged chilling in normal intact rats resulted in hyperglycemia which lasted until after the 25th day. In contrast, in chilled adrenal-demedullated animals the blood sugar remained at the control level throughout this period. At the 50th day the blood sugar of normal intact animals fell to the control value and remained so thereafter. A similar fall in adrenal-demedullated rats resulted in hypoglycemia, but a rise to control values was recorded from the 75th day. Adrenocortical hypertrophy was generally more extensive in the demedullated animals than in the normal intact animals but was absent in both groups by the 130th day. We conclude that the adrenal medulla, besides helping to provide extra blood glucose during exposure to short-term chilling, is also responsible for the sustained hyperglycemia of rats chilled for prolonged periods and thus assists in their acclimation to long-term cold stress.
Studies with fluorescein-conjugated antisera to growth hormones: I. Localization of antisera in the pituitary in various species
Authors: Nayak R. , McGarry Eleanor E. , Beck J. C.
Published: April 2011

Immunofluorescence studies showed that, in the species investigated, antisera to growth, hormones localize only in the acidophils of the pituitary gland. Cross-reactions between antigens can be detected by use of this technique even when other methods have failed.
Relationship between pancreozymin and cholinergic stimulation of pancreatic secretion
Authors: Nakamura M. , English G. , Magee D. F.
Published: April 2011

In conscious pancreatic-fistula dogs with low gastroenterostomies the interactions of pancreozymin (PZ) with methacholine were studied. Combinations of methacholine and PZ depressed amylase, lipase, and total protein secretion when doses were high, i.e. above 2 units/min PZ with 2 μg/min methacholine as background, and above 4 μg/min methacholine with 2 units/min PZ as background. Atropine depressed the enzyme response to Boots but not to Jorpes PZ. It did not alter the depression produced by high doses of PZ and methacholine in combination. These data are consistent with the view that the actions of PZ and methacholine on enzyme production are closely related.
The effect of decreased feeding frequency on body composition in mature and immature male and female rats
Authors: Wardlaw Janet M. , Hennyey Donna J. , Clarke Ruth H.
Published: April 2011

Ninety-day-old male and female rats of the Wistar strain were force-fed a liquefied diet twice daily for a 2-week experimental period. The amounts fed corresponded to ad libitum intakes of similar groups of animals fed the diet in the dry state. The animals were adjusted to the feeding technique for 1 week prior to the experimental period. At the end of the experimental period the carcasses of the force-fed animals and the ad libitum control groups were analyzed for fat, nitrogen, and moisture content. The frequency of feeding had no significant effect on percentage carcass fat, but lessened frequency of feeding was associated with a decrease in percentage carcass protein (N × 6.25) which was of slight significance. Subsequently, 35-day-old animals were treated similarly. In the younger animals the method of feeding had a significant effect on carcass fat, with an increase in fat content in the force-fed animals which was apparent in the males but was not of significance in the females. The increased fat deposition in the immature male animals was accompanied by a decreased weight gain. A significant decrease in percentage carcass protein was observed in the immature force-fed animals.
The comparative effect of reserpine and carbethoxysyringoyl methylreserpate (Su 3118) upon the menstrual cycle of the rhesus monkey
Authors: Erikson Lloyd B.
Published: April 2011

Female rhesus monkeys were treated with either reserpine or carbethoxysyringoyl methylreserpate (Su 3118) during the proliferative phase (days 2 through 12) of the menstrual cycle, at the time of the year (fall–winter season) when menstrual cycles were very regular. When reserpine was given at dosages of 1.0, 0.5, and 0.2 mg/kg body weight, 11 out of 17 menstrual cycles were prolonged. When carbethoxysyringoyl methylreserpate was given at similar dosage, 6 out of 15 menstrual cycles were prolonged, and no significant difference in comparative effectiveness of the two drugs was found. Data from vaginal smears and washes were presented to suggest that drug action was mediated through an estrogen-withdrawal effect. Since the former drug has marked tranquilizing property while the latter drug does not, it would appear that marked tranquilization is not a prerequisite for this endocrinopathy.
Effect of norepinephrine, isoproterenol, and adrenergic blockers upon the intrarenal distribution of blood flow
Authors: Carrière Serge
Published: April 2011

The effect of intrarenal administration of norepinephrine, isoproterenol, and adrenergic blockers upon the intrarenal distribution of blood flow has been studied with the 85Kr method. Norepinephrine produces marked vasoconstriction of the outer cortex while it increases the medullary blood flow rate. Isoproterenol had no effect of its own and antagonized the norepinephrine effect. Phenoxybenzamine produced no particular effect and prevented the hemodynamic modifications produced by norepinephrine. Phenoxybenzamine also unmasked the cortical vasodilating effect of isoproterenol. Propranolol was found to have an adrenergic-like effect on the cortical and medullary circulations which was inhibited by phenoxybenzamine. It is concluded that the cortical circulation is very reactive to vasoactive stimuli whereas the outer medulla seems to present a rather passive vascular bed.
Testosterone dependency of the lethal factor in mouse submandibular gland isografts
Authors: Lin C. D. , Hoshino K.
Published: April 2011

In previous papers we have described the presence of the lethal factor which was exerted by the submandibular glands transplanted from adult male donor mice autologously and isologously. The lethal factor was not demonstrated by submandibular grafts obtained from immature male or adult females. We then hypothesized that the lethal factor may be directly related to sexual maturation of male donors and also to an action of testosterone. To clarify this hypothesis, the present experiments were carried out, and the results obtained indicate that the lethal factor is testosterone-dependent. Submandibular grafts obtained from both immature male and adult female donors which received pretreatment with testosterone enanthate exerted a lethal effect on the hosts. Large dosages of testosterone enanthate, which obviously increased the lethal factor level in the submandibular gland, did not kill normal intact adult mice; nor did it increase the mortality of bilaterally submandibular-sialoadenectomized immature mice beyond that of controls without testosterone treatment, when they were not transplanted. Although the site of production of the lethal factor is unknown, we postulate that the submandibular gland is the source.
The exchange of glucose across the liver cell membrane
Authors: Hetenyi Jr. G. , Norwich K. H. , Studney D. R. , Hall J. D.
Published: April 2011

A set of equations was worked out to estimate the rapidity of the outward penetration of glucose from the hepatic intracellular compartment into the plasma compartment. In dynamic steady states at different blood sugar levels the average rate constant was found to be 0.46 min−1. Thus the rate at which glucose leaves the liver cell is rapid, but not instantaneous. The flux rates of glucose across the liver cell membrane were calculated and were found to be approximately eight times higher than the rate of glucose production. Two non-metabolizable glucose analogues, L-glucose and 3-O-methylglucose, were found to be distributed in 85% of the total water content of the liver.
Evidence for a humoral factor modifying the renal response to blood volume expansion in the rat
Authors: Pearce J. W. , Sonnenberg H. , Veress A. T. , Ackermann U.
Published: April 2011

In this study, designed to examine the interaction of mechanisms regulating renin secretion with those producing "volume diuresis and natriuresis", rats depleted of renin by chronic salt-loading and desoxycorticosterone (DOCA) administration (DOCA rats) showed exaggerated responses to iso-oncotic blood volume expansion. Conversely, chronically salt-deficient rats (NaD rats), known to have high renin levels, showed very depressed responses to expansion. Isovolemic cross-circulation of DOCA and NaD rats, including exchange of the animals' blood with bovine albumin solution in a reservoir, largely restored the renal response of NaD rats to subsequent infusion from the reservoir without altering responsiveness of the DOCA rats. Changes in plasma sodium, hematocrit value, and vascular pressures following cross-circulation were not different from those which followed exchange without cross-circulation in control experiments. In the latter, the renal response of NaD rats remained depressed, a finding not altered by acute administration of DOCA. The modification of response in cross-circulated NaD rats was therefore attributed to transfer of a humoral factor which interacted with the volume regulatory mechanism. Such a factor could be anti-renin, or alternately, a humoral effector, the level of which was critically increased in NaD rats before expansion.
The importance of the adrenergic beta-receptors for thermogenesis and survival of acutely cold-exposed mice
Authors: Estler C.-J. , Ammon H. P. T.
Published: April 2011

In normal warm-adapted mice a lowering of the ambient temperature to 0 °C was followed by piloerection, shivering, and an increase of oxygen consumption, which prevented a serious hypothermia. The survival rate after 4 h cold exposure was 82%. Mice pretreated with a β-receptor blocking agent, propranolol, MJ 1999, or INPEA, showed piloerection and shivering when exposed to 0 °C, but their ability to increase heat production was impaired. Depending upon the dose of the β-receptor blocking agent used, the increase in the metabolic rate was diminished, and rectal temperature and survival rate dropped sharply. After 25 μg/g MJ 1999, only 13% of the animals survived. After 20 μg/g propranolol or 100 μg/g INPEA all animals died. The results give evidence for the importance of the sympatho–adrenal system in general for the maintenance of body temperature and the survival after acute cold exposure, and for the special importance of the adrenergic β-receptors, which are necessary for the animals to increase their heat production.
Interaction of saponins with cholesterol, lecithin, and albumin
Authors: Schlösser E.
Published: April 2011

Fifteen saponins and six sapogenins were tested for their reaction to cholesterol, lecithin, and albumin. All compounds formed a complex with cholesterol, but not with lecithin or albumin. The prevention of saponin-induced hemolysis by bovine serum appeared to be correlated with its content of free cholesterol. Active saponins had a high affinity for cholesterol, which was not observed with hemolytically inactive compounds. According to these results, the sterols located in the cell membranes appear to be the site for the membranolytic action of saponins.
Biochemical studies on the anticalcinotic effect of sodium salicylate
Authors: Berczi I. , Somogyi A.
Published: April 2011

Experimental soft-tissue calcification was induced in the hind paw of rats injected intravenously with lead acetate and locally with egg white. This mineralization was inhibited by treatment with sodium salicylate given orally. Sodium salicylate did not influence the extravasation of lead in the treated paw, but decreased the lead-induced hypercalcemia and hyperphosphatemia. A parallelism was found between the blood levels of calcium, phosphorus, and lead. A secondary deposition of lead was evident in the heavily calcified paws.
The effect of vasodilator drugs on the noradrenaline constrictor response in the isolated mesenteric artery
Authors: McNeill John H. , Barnes Rex V. , Davis Ronald S. , Hook Jerry B.
Published: April 2011

Previous reports have indicated that diazoxide will inhibit the vasoconstrictor response to noradrenaline on isolated aortic strips (Wohl et al. Life Sci. 7, 381 (1968)). Inhibition of the noradrenaline response was dependent on the calcium concentrations. The present study has confirmed this observation in an isolated perfused mesenteric artery preparation. In addition, a calcium-dependent inhibition of the noradrenaline constrictor response was found with theophylline and sodium nitrite but isoproterenol did not inhibit the noradrenaline response. It is suggested that the drugs which inhibit noradrenaline may do so by either blocking calcium receptors or by depleting an intracellular calcium pool necessary for drug-induced vasoconstriction; or by preventing calcium release from such a pool. Blockade of alpha adrenergic receptors is probably not involved since the drugs also blocked the constrictor response to vasopressin. The mechanism of the inhibitory action of these drugs is probably not related to their effects on cyclic AMP.
Blockade by triptyline compounds of tyramine uptake and of tyramine-induced phosphorylase activation in cardiac tissue
Authors: McNeill John H. , Commarato Michael A.
Published: April 2011

Pretreatment of rats with amitriptyline, nortriptyline, or protriptyline significantly decreased the effect of tyramine on cardiac phosphorylase and also significantly decreased the uptake of tyramine-3H as measured by the amount of octopamine-3H found in the heart. The order of efficacy of the drugs in blocking both the effect and the uptake of tyramine was protriptyline > nortriptyline > amitriptyline. The compounds studied have been reported to have this same order of efficacy in blocking the uptake of norepinephrine or in enhancing the norepinephrine response. The data presented support the hypothesis that tyramine utilizes the same uptake system as does norepinephrine and that drugs which enhance the effects of norepinephrine and decrease the effects of tyramine do so by preventing the uptake of the amine. The data also support the concept that within a chemical series the secondary amine is more effective than the corresponding tertiary amine in blocking adrenergic amine uptake.
Selenium distribution and radiotocopherol metabolism in the pregnant ewe and fetal lamb
Authors: Hidiroglou M. , Hoffman I. , Jenkins K. J.
Published: April 2011

Selenium concentrations were determined at various stages of gestation in the bodies and fetal tissues of 26 ewes fed a nutritional muscular dystrophy (NMD) producing hay for 2 years. Eight of these ewes were injected intramuscularly with 6 mg selenium 10 days before slaughter. Maternal tissues in general contained more selenium than the corresponding fetal tissues. As might be expected, the injection of selenium enhanced tissue concentrations in both ewes and fetuses. The pattern of selenium concentration in the various tissues was similar in dams and fetuses, with kidneys containing highest amounts. Selenium concentrations in the tissues of both ewes and fetuses did not appear to change with the stage of gestation. A single oral dose of radiotocopherol was administered to each of 10 pregnant ewes which had been fed an NMD-inducing hay for 2 years. Animals were slaughtered at 1, 2, 5, and 13 days after the oral dose of vitamin E. It was found that in the ewes, liver and adrenal tissues had a high rate of tocopherol uptake in the first 24 h. Subsequently, the radioactivity fell sharply with time, whereas in heart, muscle, kidney, and lung tissues, in which the initial uptake was lower, the decrease with time was slower. Relative specific activities between maternal and corresponding fetal tissues tended to decrease with time. The ewes excreted more than 70% of the administered radiotocopherol dose within 4 days, primarily via the feces; urinary excretion was comparatively small.
Prevention of indomethacin-induced intestinal ulcers by spironolactone and norbolethone
Authors: Selye H.
Published: April 2011

Both spironolactone (an antimineralocorticoid compound) and norbolethone (an anabolic steroid) protect the rat against the production of multiple intestinal ulcers and peritonitis by indomethacin.
Stimulation of sugar transport by a factor released from gas-perfused hearts
Authors: Bihler I. , Hollands Mary , Dresel Peter E.
Published: April 2011

When gas-perfused kitten hearts are perfused intermittently with small volumes of Krebs solution, the effluent contains a material which precipitates with 0.25 saturation with ammonium sulfate. This material increased the uptake of nonmetabolized sugars and amino acids by isolated skeletal muscle, the uptake of glucose by adipose tissue, and the deposition of glycogen in muscle. The material was different from insulin as determined by immunoassay. The increment in sugar uptake could not easily be demonstrated to be dependent on the concentration, owing to the considerable variability of the total activity and to a depressant effect appearing with higher concentrations. There appeared to be no correlation between the cardiac positive inotropic activity reported previously and the activation of membrane transport by this material. The material is very similar to the muscle activity factor described by others.
The effect of changing interfacial tension on the shape of the red cell
Authors: Shrivastav B. B. , Burton A. C.
Published: April 2011

Previous biophysical research on the equilibrium of the red cell membrane in the normal biconcave, and the other shapes assumed in osmotic swelling, has led to a relation for the dimple region, between the tension in the membrane, its curvature, and an internal pressure. The relation is tested on a new shape produced by adding 0.004% by volume of Tween 80. The opposite membranes near the axis of revolution of the cell become parallel over a disc of diameter 2.6 μ, at a distance of 0.77 μ apart (30% less than the nearest distance in normal cells). The 'dimple' region becomes more like a 'moon crater'. The volume of the cell is not significantly altered, but the surface area increases by about 14%. The shape is consistent with a decrease in interfacial tension of the membrane, and the area increase is similar to that found by Seeman for agents which enter into the membrane. The hypothesis of internal structure across the central part of the cell, indicated by previous studies of birefringence, is supported by the observations on this new shape.
Nonuniform distribution of microspheres in blood flowing through a medium-size artery
Authors: Phibbs Roderic H. , Dong L.
Published: April 2011

Suspensions of rigid microspheres, varying from 7.5 to 80 μ diameter, were injected into the left ventricle or ascending aorta of five anesthetized rabbits. After injection, an exposed branch of the femoral artery was frozen ultrarapidly, then removed; after histologic preparation, serial cross sections were studied microscopically. The radial distribution of the spheres within the vessel lumen was uneven, with a progressively decreasing concentration peripherally. This appeared to be proportional to sphere diameter and extended too far in from the periphery to be explained by entrance effect only. Microspheres of 7.5 to 10 μ diameter had the radial distribution which most closely approached that of erythrocytes in these same arteries.
Potentiation of responses to histamine in aortic strips by steroids
Authors: Kalsner Stanley
Published: April 2011

Responses to histamine were potentiated by 17β-estradiol in untreated and reserpine-treated aortic strips. 17β-Estradiol produced significantly greater potentiation after inhibition of diamine oxidase with iproniazid. Amodiaquine and quinidine, two known inhibitors of imidazole-N-methyltransferase, enhanced responses to histamine and abolished the potentiating effect of 17β-estradiol. Also, contractions produced by histamine were not increased by amodiaquine or quinidine in the presence of 17β-estradiol. Responses to histamine were increased only slightly by testosterone and hydrocortisone, and these effects were also blocked by known inhibitors of N-methylation. Responses to 1,4-methylhistamine, the N-methylated metabolite of histamine, were not enhanced by 17β-estradiol or amodiaquine, and in only one of six strips by quinidine. Studies with the oil immersion technique indicated that imidazole-N-methyltransferase is a major mechanism terminating the action of histamine in aortic strips. The rate of N-methylation was significantly decreased by amodiaquine, quinidine, and 17β-estradiol. It is concluded that the steroid hormones enhance responses of vascular tissue to histamine by inhibiting N-methylation. Contractions of rabbit ileum by histamine were not increased by 17β-estradiol, perhaps owing to a dominant depressant effect of the steroid on the amplitude of spontaneous contractions.
Systolic pressures in the extremities of man with special reference to the toes
Authors: Lezack J. D. , Carter S. A.
Published: April 2011

Systolic pressures have been studied extensively in the fingers but not in the toes. We measured systolic pressures in the toes, fingers, ankles, and wrists of young normal subjects during body heating and cooling. Systolic end points were determined during deflation of pneumatic cuffs by detecting either the appearance of oxyhemoglobin in the skin using a spectroscope, or the increase in the volume of the part using a strain gauge plethysmograph. Toe and finger pressures were higher during vasoconstriction than during vasodilatation (p < 0.001), whereas the ankle-to-toe and wrist-to-finger gradients were higher during vasodilatation (p < 0.005), These changes in pressures and gradients with change in vasomotor state are probably due to alterations in flow through the arteries of the hand and foot and the associated changes in the utilization of pressure energy. Finger pressures were higher than toe pressures during both vasomotor states (p < 0.025). This was only partly explained by the difference in hydrostatic pressure (toes higher than fingers with respect to heart in supine position). The tendency for gangrene to develop in the toes may be related in part to their lower pressures.
The effect of dietary fluoride on calcium and phosphorus metabolism of rats
Authors: Deshmukh D. S. , Méranger J. C. , Shah B. G.
Published: April 2011

Two groups of 12 weanling rats were fed for 4 weeks diets containing 0.2 and 200 p.p.m. fluoride. All rats were then injected with 45CaCl2 and a week later a balance trial was conducted. At the end of the trial the rats were killed, and long bones, liver, kidney, and plasma collected. There were no significant differences between the two groups in the endogenous fecal Ca or absorption or retention of calcium, but the percent retention of phosphorus by the high fluoride group was 15% greater than that by the controls. Although fluoride feeding did not affect the ash, calcium, and phosphorus contents of the bones or the turnover of bone mineral, it caused a significant increase in the water content and a decrease in the breaking load of the femur shafts. When the effect of body weight on bone strength was eliminated from the fluoride group, there was no significant difference in the breaking load. The level of fluoride in the soft tissues of the treated rats was 3 to 8 times that in the corresponding tissues of the controls. The alkaline phosphatase activity in the bone and plasma of the treated rats was higher and the acid phosphatase activity in bone lower than the comparable values for the controls.