bluuebunny/crossref_metadata_2025 huggingface dataset:
VEGF and bFGF stimulate myocardial vascularization in embryonic chick
Authors: Tomanek Robert J. , Lotun Kapildeo , Clark Edward B. , Suvarna Padma R. , Hu Norman
Published: December 2017

We tested the hypothesis that early vascularization of the embryonic heart is enhanced after bolus injections of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) into the vitelline vein before the onset of myocardial vasculogenesis (3.5 days, stage 21). Electron and light microscopy were utilized to obtain morphometric data. At stages 29 and 31, myocardial vessel volume or numerical density were higher in embryos injected with 50 ng bFGF than in the saline-injected controls. A VEGF injection increased vascular volume density at stage 29 and both volume and numerical density at stage 31. bFGF, but not VEGF, was associated with an enhancement of the sinusoidal system (spongy layer of the ventricle) at stage 29. This effect disappeared by stage 31. In conclusion, 1) enhancement of bFGF or VEGF before myocardial vascularization increases vascular growth, but the initial effect of bFGF is greater; 2) the effects of these growth factors on vascular volume and numerical density are temporally dependent; and 3) bFGF, in addition to its effects on the coronary vasculature, influences ventricular modeling by apparently acting on myocytes as well as endothelial cells.
Ventricular remodeling in a mouse model of myocardial infarction
Authors: Patten Richard D. , Aronovitz Mark J. , Deras-Mejia Luz , Pandian Natesa G. , Hanak George G. , Smith John J. , Mendelsohn Michael E. , Konstam Marvin A.
Published: December 2017

We investigated the suitability of studying ventricular remodeling in a mouse model of myocardial infarction (MI). We performed left coronary ligation ( n = 22) or a sham procedure ( n = 21) on normal C57BL/6J mice. Six weeks later, animals underwent echocardiography and hemodynamic evaluation. Left ventricular (LV) volume at a common distending pressure was calculated from passive pressure-volume curves. The MI group exhibited lower systolic blood pressure ( P < 0.05), higher LV end-diastolic pressure ( P < 0.05), and lower peak first derivative of LV pressure (dP/d t, P < 0.05) than the sham group. Mice with moderate (<40%, n = 11) and large (≥40%, n = 11) MIs displayed increased LV mass-to-body weight ratio ( P < 0.02 and P < 0.01, respectively, vs. sham group), whereas only the large-MI group exhibited increased right ventricular mass-to-body weight ratio ( P < 0.01). LV volumes were increased in the moderate-MI group ( P= 0.059 vs. sham group) and to a much greater extent in the large-MI group ( P < 0.0001 vs. sham group). The moderate- and large-MI groups also exhibited increases in LV end-diastolic diameter ( P < 0.03 and P < 0.0001, respectively, vs. sham group) and LV end-systolic diameter ( P< 0.01 and P < 0.0001, respectively, vs. sham group) with decreased fractional shortening ( P < 0.01 for both). These data demonstrate ventricular remodeling in a mouse model of MI and confirm the feasibility of quantifying indexes of remodeling in vivo and postmortem. This model will be of particular usefulness when applied to transgenic strains.
Role of opioids in hypoxic pial artery dilation is stimulus duration dependent
Authors: Armstead William M.
Published: December 2017

Because methionine enkephalin contributes to and dynorphin opposes dilation during a 10-min hypoxic exposure, opioids modulate pial artery dilation to this stimulus. However, such modulation may be dependent on the duration of hypoxia. The present study was designed to characterize the modulation of hypoxic pial dilation by opioids as a function of stimulus duration in newborn pigs equipped with a closed cranial window. Hypoxic dilation was decremented in both moderate and severe groups ([Formula: see text] ≈ 35 and 25 mmHg, respectively) during 20-min and 40-min exposure periods compared with the response during 5 or 10 min of stimulation (24 ± 1, 25 ± 1, 18 ± 1, and 14 ± 1% for 5, 10, 20, and 40 min of moderate hypoxia; means ± SE). Moderate and severe hypoxia had no effect on cerebral spinal fluid (CSF) methionine enkephalin or dynorphin concentration during a 5-min exposure period. During a 10-min exposure, however, both opioids were increased in CSF. During 20- and 40-min exposure periods, CSF dynorphin continued to increase, whereas methionine enkephalin steadily decreased (962 ± 18, 952 ± 21, 2,821 ± 15, 2,000 ± 81, and 1,726 ± 58 pg/ml methionine enkephalin for control, 5, 10, 20, and 40 min of moderate hypoxia, respectively). The μ-opioid (methionine enkephalin) antagonist β-funaltrexamine had no influence on dilation during the 5-min exposure, decremented the 10- and 20-min exposures, but had no effect on 40-min exposure hypoxic dilation. Whereas the κ-opioid (dynorphin) antagonist norbinaltorphimine similarly had no effect on a 5-min exposure dilation, it, in contrast, potentiated 10-, 20-, and 40-min exposure hypoxic dilations (23 ± 1 vs. 23 ± 1, 24 ± 1 vs. 32 ± 1, 16 ± 1 vs. 24 ± 2, and 13 ± 1 vs. 23 ± 3% for 5, 10, 20, and 40-min hypoxic dilation before and after norbinaltorphimine). These data show that opioids do not modulate hypoxic pial dilation during short but do so during longer exposure periods. Moreover, hypoxic pial dilation is diminished during longer exposure periods. Decremented hypoxic pial dilation during longer exposure periods results, at least in part, from decreased release of methionine enkephalin and accentuated release of dynorphin. These data suggest that the relative role of opioids in hypoxic pial dilation changes with the stimulus duration.
Cardiovascular, endocrine, and body fluid-electrolyte responses to salt loading in mRen-2 transgenic rats
Authors: Li Ping , Morris Mariana , Ferrario Carlos M. , Barrett Cindy , Ganten Detlev , Callahan Michael F.
Published: December 2017

We previously demonstrated that mRen-2 transgenic [Tg(+)] rats are sensitive to chronic high NaCl intake, showing increased arterial pressure and vasopressin (VP) secretion. In this study, we determined the effect of a chronic osmotic challenge, 4 days of drinking 2% NaCl, on direct arterial blood pressure, heart rate, fluid-electrolyte balance, circadian rhythm of mean arterial pressure (MAP), and changes in plasma VP and catecholamines. Under baseline conditions, male Tg(+) rats showed a significant shift in the peak in circadian MAP into the light portion of the day-night cycle. Substitution of 2% NaCl for drinking water caused a rapid increase in MAP, 20 ± 5 mmHg in Tg(+) rats within 6 h. Whereas the amplitude of circadian MAP fluctuations increased in salt-loaded Tg(+) rats, there was no significant change in the circadian timing of peak MAP with salt loading. Tg(+) rats showed exaggerated osmotic-induced increases in plasma VP, norepinephrine (NE), and epinephrine (Epi) compared with Tg(−) rats. Plasma NE and Epi were increased two- and fourfold, respectively, in the hypertensive rats with no significant change in the Tg(−) rats. Intravenous administration of a VP antagonist did not alter arterial pressure in either Tg(+) or Tg(−) rats. Tg(+) and Tg(−) rats showed a positive sodium balance with no significant difference observed between the groups. Tg(+) rats showed a significant increase in salt consumption, plasma sodium, osmolality, and hematocrit, accompanied by a negative water balance. We conclude that Tg(+) rats are sensitive to acute and chronic osmotic stimuli in terms of blood pressure, fluid-electrolyte balance, and plasma VP and catecholamines. Whereas elevated plasma VP does not contribute to the hypertensive response, increased sympathetic drive may mediate the salt-induced blood pressure changes in this model.
Mechanosensitive ion channels in putative aortic baroreceptor neurons
Authors: Kraske Shane , Cunningham J. Thomas , Hajduczok George , Chapleau Mark W. , Abboud Francois M. , Wachtel Ruth E.
Published: December 2017

Cell-attached patch-clamp experiments were performed on dissociated neurons from nodose ganglia of adult rats. Putative aortic baroreceptor neurons were identified by labeling nerve endings in the adventitia of the aortic arch with the carbocyanine dye DiI. Whereas previous experiments demonstrated the presence of mechanosensitive (MS) whole cell currents, these experiments studied single MS ion channels and examined the influence of culture conditions on their expression. Single MS channels were activated by applying negative pressure through the recording pipette. Channel openings became more frequent as the negative pressure was increased, with open probability increasing significantly above 30 mmHg. MS channels had a slope conductance of 114 pS and a reversal potential of ∼0 mV, consistent with a nonspecific cation conductance. Channels were not affected by antagonists of voltage-gated conductances but were blocked by 20 μM gadolinium, a known blocker of MS ion channels. When nodose neurons were cocultured with aortic endothelial cells, but not aortic smooth muscle cells, the percentage of patches exhibiting MS ion channels increased significantly, suggesting that aortic endothelial cells secrete a diffusible factor that increases channel expression.
Role of Hypophysis and Adrenals in Fatty Infiltration of Liver Resulting From Acute Ethanol Intoxication
Authors: Mallov Samuel , Bloch Janet L.
Published: December 2017

Acute ethanol intoxication was found to promote the fatty infiltration of liver in rats. The liver lipid concentrations gradually rose to peak values, then slowly returned to normal. The duration of the fatty infiltration, and the peak liver lipid values obtained, were functions of the dose of ethanol administered. Female rats showed a more severe fatty infiltration than did males, under the same conditions. The prior administration of large quantities of choline reduced the intensity of the fatty infiltration provoked by the ethanol. In contrast to intact animals, neither adrenalectomized nor hypophysectomized rats showed an accumulation of liver lipids as a result of acute ethanol intoxication. Adrenalectomized rats maintained on cortisone, and adrenal demedullated rats, however, showed the same liver lipid response to ethanol as did intact rats. Rats chronically intoxicated for a period of 30 days exhibited hypertrophy of the adrenals. Acute intoxication produced by isopropanol administration also resulted in the accumulation of liver lipid. It is suggested that ethanol intoxication may cause the mobilization of fat from the depots to the liver, and that pituitary and adrenal cortical hormones are involved in the mechanism of this mobilization.
Effect of Nicotinic Acid and Derivatives on Rat Liver Regeneration
Authors: Gershbein Leon L.
Published: December 2017

Diets containing elevated levels of nicotinic acid as such or in the form of the sodium salt (0.25% as based on the acid) or nicotinamide (0.35% and 0.65%) decreased the extent of liver regeneration in partially hepatectomized rats. Isonicotinic acid hydrazide (0.25%) and kynurenic acid (0.35%) were without effect. Coraminc (0.35–1.0%) by this route or by subcutaneous injection markedly increased the rate. In contrast to the diets, nicotinic acid or amide force fed as a large single daily dosage or nicotinic acid administered subcutaneously did not influence the extent of liver regeneration. The incorporation of 0.35% choline in a ration containing 0.35% nicotinamide negated the effect due to the amide, no statistically significant change over the control rate being apparent.
Oxidation of Palmitic Acid-1-C14 by Tissues of Carbohydrate and Fat Diet-Adapted Rats
Authors: Tepperman Jay , Tepperman Helen M. , Schulman Martin P.
Published: December 2017

Groups of adult male rats were adapted to isocaloric high fat and high carbohydrate diets for 4–6 weeks. Liver slices and segments of diaphragm were incubated in a medium to which an emulsion containing palmitic acid-1-C14 had been added. Respiratory CO2 was collected, precipitated as BaCO3, and the specific activity estimated. Liver slices of fat diet-adapted rats oxidized more of the added palmitic acid than did those of carbohydrate-fed controls. Diaphragms of the former group also oxidized more added palmitic acid but abstracted less glucose from the medium than did those of the latter.
Effects of Digitalis and Hypoxia on Potassium Transfer and Distribution in the Dog Heart
Authors: Conn Hadley L.
Published: December 2017

The effects of moderately severe hypoxia and moderately large doses of digitalis on potassium kinetics and distribution in the left ventricle of the normal intact dog were studied after the apparent establishment of a new steady state. Digitalis and hypoxia, more so, caused reduction in interstitial-intracellular potassium transfer rates and rate constants, and modest to moderate reduction in cell and interstitial potassium. Hypoxia also caused marked increase in plasma-interstitial potassium exchange rate and rate constants apparently due to the increased coronary blood flow resulting from hypoxia. The effects of digitalis on ISF-ICF transfer are compatible with the thesis that a major action of digitalis is the partial inhibition of of potassium transfer into the myocardial cell. The results from the steady state hypoxia experiments show that aerobic metabolism is necessary for at least a considerable fraction of potassium transfer in the heart.
Metabolism of Carboxyl-Labeled Short Chain Fatty Acids by the Isolated Dog Heart
Authors: Cavert H. Mead , Johnson John A.
Published: December 2017

A comparative study has been made of the metabolism of short chain carboxyl-labeled fatty acids to CO2 and to glycogen in the isolated dog heart perfused with heparinized blood by the Langendorff technique. In confirmation of previous work by others, at high concentrations of administered acetate-I-C13 this compound contributed from 30–40% of respiratory CO2. Increasing the level of administered acetate correspondingly elevates the contribution of acetate carbon to CO2. The portion of total CO2 derived from 2-, 3-, 4- and 8-carbon fatty acids appeared comparable (5%) at substrate levels of 1–2 mm/l. However, at 12–14 mm/l. the values were 20, 5, 3 and 3% of total CO2 derived from the C13-labeled carboxyl carbon of acetate, propionate, n-butyrate and n-octanoate, respectively. On the assumption of equal rates of combustion of all carbon atoms in each compound, the percentages were 41, 15, 13 and 25%, respectively, of CO2 derived from the administered labeled substrate. Labeled sodium formate was not rapidly converted to respiratory CO2 in a single isolated heart experiment. Carboxyl carbon from none of the labeled fatty acids contributed detectably to carbon of cardiac glycogen.
Formation of Effective Collateral Circulation Following Excision of Hepatic Artery
Authors: Jefferson N. C. , Hassan M. I. , Popper H. L. , Necheles H.
Published: December 2017

The present work is an anatomical demonstration of the collateral blood supply which maintains the liver after acute interruption of the hepatic artery. This is demonstrated with x-ray films and corrosion specimens of the livers of dogs weeks to months following excision of the hepatic artery. The livers were injected with red lead suspension or with a plastic material. With both methods, we have demonstrated the development of adequate anastomoses within the liver between the phrenic and the hepatic arteries. The phrenic arteries had hypertrophied considerably and numerous good sized anastomoses with the hepatic arteries were present, allowing for an adequate supply of arterial blood to the liver and survival of the animal. In similar control experiments on normal dogs, the phrenic arteries were small, and insignificant anastomoses to the hepatic arteries were found.
Cardiovascular Effects of Anesthetic Doses of Pentobarbital Sodium
Authors: Nash Clinton B. , Davis Floyd , Woodbury Robert A.
Published: December 2017

The effects of continuous pentobarbital anesthesia on certain features of the cardiovascular system were investigated in trained male dogs. Similar results were obtained in 10 animals using the pressure-pulse contour method and in 5 animals by the dye dilution technique. Cardiac output fell progressively during the first 2–3 hours, the maximum fall exceeding 44% of control value, and was statistically significant from the 1-hour observation throughout the remainder of the 7-hour experimental period. Except for the brief period during induction, mean blood pressure did not deviate markedly from that of the unanesthetized animal. The fall in hematocrit during the 1st hour was followed by a slow partial recovery. Plasma proteins decreased both in concentration and absolute amount, while plasma volume showed a slight rise. The widely used anesthetic dose of 30 mg/kg seems needlessly high, and may be expected to induce cardiovascular changes even greater than those reported herein. This study has demonstrated clearly that a severe decrease in cardiac output occurs under continuous pentobarbital anesthesia in the dog. While the mechanism responsible for this fall has not been elucidated, it appears likely that a direct action on the myocardium may be involved. From the data presented it seems clear that published works which did not include specific control experiments for the effect of the anesthetic agent used require critical re-evaluation. This precaution is especially necessary in cardiovascular experiments involving pentobarbital anesthesia, since the data here reported indicate that this anesthetic agent itself produces marked changes in the cardiovascular system.
Effect of Potassium-Rich Medium, of Glucose and of Transfer of Tissue on Oxygen Consumption by Rat Diaphragm
Authors: Zierler Kenneth L.
Published: December 2017

Oxygen consumption of the rat diaphragm is the same during incubation in each of these media: Krebs-Ringer-phosphate, calcium- and magnesium-free Krebs-Ringer-phosphate, a potassium-rich medium and a potassium-rich medium plus glucose, providing incubation is not interrupted by transfer of diaphragm to fresh media. When the diaphragm is manipulated (sham transfer) after an initial incubation there is a reduction of 10–15% in oxygen consumption. When, after an initial incubation, the diaphragm is transferred to fresh media there is a further decrease in oxygen consumption which is greatest in glucose-free media and least in the glucose-containing medium. When, after transfer and reincubation in a fresh flask, the diaphragm is returned to its initial flask and reincubated there is relative restoration of its oxygen consumption. These observations suggest that oxidizable endogenous substrates diffuse from the diaphragm during incubation.
Regulation of Respiration During Muscular Activity
Authors: Kao Frederick F.
Published: December 2017

The mechanism of exercise hyperpnea was investigated employing a cross-circulation technique in which the head of a dog (humoral dog) was perfused exclusively by blood from another dog (neural dog) by way of the carotid arteries and the external jugular veins. The lower extremities of both dogs were induced to exercise separately by stimulating with 60-cycle alternating current, which is modulated sinusoidally. Forty-four experiments were performed on nine pairs of such preparations. The ventilation of the neural dog (exercising) first overshot, then attained a steady state, but the ventilation of the humoral dog overshot to a much higher level when its hind legs were exercised. During the steady state the ventilation of the neural dog (when it was exercising) increased in direct proportion to oxygen consumption. The slope of the regression line expressing the increment in ventilation as a function of oxygen consumption in the neural dog is 0.0298, which is not statistically different from that established for intact dogs during induced exercise or from that in normal dogs during voluntary exercise. The humoral dog whose head was perfused by arterial blood from the exercising neural dog showed no change in ventilation. Therefore, it is concluded that there is no humoral agent produced in the arterial blood of a dog subjected to this type of exercise. The normalcy of the respiratory apparatus in the humoral dog after the establishment of the cross circulation was tested by CO2 inhalation and lobeline administration and it was found to be adequate.
Measurement of Extracellular Fluid Volume of Nephrectomized Dogs With Mannitol, Sucrose, Thiosulfate and Radiosulfate
Authors: Mulrow Patrick J. , Oestreich Herbert M. , Swan Roy C.
Published: December 2017

Volumes of distribution of mannitol, sucrose, thiosulfate and radiosulfate have been measured simultaneously in nephrectomized dogs. The volume of distribution of each substance is reproducible when the substance is reinfused 6 hours later. There appears to be no increase in the extracellular fluid volume during this interval as a result of the nephrectomy. The logarithm of the concentration of mannitol, sucrose and radiosulfate continues as a simple exponential function of time from the 3rd to 30th hour after their infusion. The volumes of distribution of mannitol and radiosulfate reflect increments in extracellular fluid with fair accuracy, while the sucrose distribution measures only 72% of a 1-liter expansion of extracellular fluid. There are serious limitations in the application of thiosulfate distribution to such measurements.
Effect of Liver on Lipolysis by Normal and Postheparin Sera in the Rat
Authors: Spitzer Judy A. , Spitzer John J.
Published: December 2017

Lipolysis by sera heparinized in vivo and by normal sera was studied after perfusion through isolated rat liver. The rate of clearing of an oil emulsion by serum containing clearing factor was decreased after perfusion through the liver. The extent of clearing was not always affected. Clearing factor activity was lessened by incubation with heparinase (prepared from rabbit livers). Normal rat serum exhibited consistent lipolytic activity following perfusion through the isolated liver. This activity was not due to clearing factor.
Behavior of the Thyroid Toward Elements of the Seventh Periodic Group
Authors: Baumann Emil J. , Searle Norma Z. , Yalow A. Aaron , Siegel Edward , Seidlin S. M.
Published: December 2017

In order further to test our hypothesis that the elements of group VII are selectively filtered from the blood and concentrated by the thyroid gland, rats were injected with Mn54, Br82 and Tc99. The distribution of these nuclides in tissues was determined 2 hours after administration. The thyroidal concentration of Mn54 was about 10 times that of serum, of Br82 1.3 times that of blood and of Tc99 11–30 times that of blood. These results together with those previously reported by us and by others show that ions of all group VII elements are concentrated by the thyroid, though to a varying extent. A study of the effect of stable seventh group ions on the uptake of Mn54, Br82, I131 and Re186 shows that large amounts of F–, Mn++ and Br– have little influence while even small quantities of I– or of Re++ markedly lower the thyroidal uptake of the heavier ions. Only a slight affinity of the thyroid for F–, Mn++, Br– is thus indicated, while that for I– and Re++ is far greater. This conclusion is substantiated by another type of experiment in which pairs of these nuclides were administered simultaneously and the fraction of each taken up by the thyroid determined. The affinity of the thyroid for Te, I and Re proved to be roughly equal and much larger than for Mn or Br. Unlike other group VII elements Mn accumulates in tissues of endodermal origin to an even greater extent than in the thyroid.
Alterations in Thyroxine-I131 and Triiodothyronine-I131 Metabolism Produced by Thyroidectomy, Hypophysectomy and Adrenalectomy
Authors: Vanarsdel Paul P. , Williams Robert H.
Published: December 2017

The distribution of radioactivity was determined in certain tissues of normal, thyroidectomized, hypophysectomized and adrenalectomized rats, previously given I131-labeled thyroxine or triiodothyronine intravenously. It was found that blood levels of radioactivity were higher in thyroidectomized and hypophysectomized animals given labeled thyroxine than in control rats. Also, the sex difference in liver concentration of thyroxine radioactivity observed in the control animals was abolished by thyroidectomy or hypophysectomy, and the proportion of liver radioactivity which was soluble in trichloroacetic acid was elevated, with respect to controls, in the females alone. Also in the thyroxine groups, testicular radioactivity was lower in the hypophysectomized males than in control rats, but ovarian radioactivity was increased by hypophysectomy. Thyroidectomy and adrenalectomy resulted in higher levels of blood radioactivity following labeled triiodothyronine, but no other significant changes were observed.
Fluoride Deposition in Different Segments of the Tibia of the Young Growing Rat
Authors: Zipkin I. , Scow R. O.
Published: December 2017

By inserting a stainless steel pin into the tibiae of young rats, it was possible to determine the gain in length at each end of the diaphysis and to identify the bone that was deposited at the ends during the experimental period (20th–51st day of life). At the termination of the experiment, the tibiae were divided into four segments, three of which contained portions of the diaphysis. The oven-dry, fat-free weight, ash and fluoride content of these segments were determined. Intraperitoneal injections of 3.15 mg of fluoride (NaF) over a 30-day period, starting at 20 days of age, had no noticeable effect on the longitudinal growth rate and mass of the various tibial segments. The ash content of the various diaphyseal segments was similarly unaffected. The percentage of fluoride (ash basis) of the proximal diaphyseal segment (all new bone) was similar to that of the middle diaphyseal segment, but 35% lower than that of the proximal epiphysis. There appears to be no consistent relationship between the degree of calcification (% ash) and the deposition of fluoride in various tibial segments at the end of 30 days in the young growing rat.
Effect of Extreme Cold Exposure on Adrenocortical Function in the Unanesthetized Dog
Authors: Egdahl Richard H. , Richards John B.
Published: December 2017

Unanesthetized dogs with polyethylene cannulas in the right lumboadrenal vein were subjected to environmental temperatures of –46 to –50°C for 2–28 hours and –75 to –79°C for 4–5 hours. Adrenal venous blood samples were collected prior to, and during the periods of cold exposure, and analyzed for 17-hydroxycorticosteroids. In both temperature ranges, a marked increase in adrenal steroid output occurred soon after the onset of exposure in the 10 dogs studied. In 9 of the 10 animals, this response persisted for 1–3 hours after which adrenal steroid secretion returned to control, pre-exposure levels, despite continued cold exposure. The intravenous administration of 40 iu of ACTH produced a subsequent increase in adrenal 17-hydroxycorticosteroid output. Healthy dogs exposed to temperatures of –47°C for 28 hours and –79°C for 5 hours did not become hypothermic.
X-Irradiation and Liver Regeneration in Partially Hepatectomized Rats
Authors: Gershbein Leon L.
Published: December 2017

The remaining liver of rats just after partial hepatectomy has been exposed to unfiltered x-ray ranging in dosages up to 20,000 r, the rest of the body being shielded. The livers showed no noteworthy pathology over an 11-day period except for the series irradiated with 20,000 r. The extent of liver regeneration in the irradiated animals did not differ statistically from that of the partially hepatectomized controls, evidently attesting to a definite radio-resistance for rat liver under these conditions.
Effects of Epinephrine, Norepinephrine and Isopropylarterenol on the Isolated Auricles of Four Mammalian Species
Authors: Garb Solomon , Penna Mario , Ganz Aaron
Published: December 2017

Epinephrine, norepinephrine and Isuprel were tested on the amplitude of contraction and rate of the auricles of the rat, guinea pig, rabbit and cat. In all species Isuprel was much more potent in its effects than the other amines. In the rat auricle Isuprel dilutions of 1 part in 20 trillion produced marked changes in rate and amplitude. Norepinephrine was the least potent of the three amines. The right auricle was more sensitive than the left. The great potency of Isuprel suggests that even the small concentrations of it or a similar amine which Lockett (1) reported finding in the adrenal gland would produce marked changes in auricular function. Therefore, it may be physiologically important. The ability of dilute solutions of Isuprel to restore a rapid spontaneous beat to an asystolic auricle suggests a possible role in the management of cardiac arrest. The marked differences in species response to the three amines may make this a useful bioassay technique. The combination of rat and guinea pig auricles should distinguish between the three amines in dilute solutions.
Micropuncture Study of Pressures in Proximal Tubules and Peritubular Capillaries of the Rat Kidney and Their Relation to Ureteral and Renal Venous Pressures
Authors: Gottschalk Carl W. , Mylle Margaret
Published: December 2017

Methods are described for direct measurement of the hydrostatic pressure in the surface tubules and capillaries of the rat kidney. In fifty-six anesthetized rats intratubular pressure averaged 13.5 ± 2.4 mm Hg. Subsequent microdissection showed that all of the 112 puncture sites so localized were in the first two-thirds of the proximal convoluted tubule. Under all conditions studied, intratubular pressure and the pressure in the peritubular capillaries were approximately the same. Intravenous injection of hypertonic dextrose solution generally produced a brief rise in intratubular and peritubular capillary pressures, which returned to their preinjection levels while the diuresis so produced continued, although at less than the maximal rate. Obstruction of the ureter of kidneys undergoing diuresis resulted in a prompt rise in intratubular pressure, which agreed closely with the simultaneously determined ureteral pressure. Elevation of the ureteral pressure with a pressure bottle had no effect on intratubular or peritubular capillary pressures until it exceeded the pre-existing intratubular and peritubular capillary pressures, and then all rose together up to a maximum intratubular pressure above which elevation of ureteral pressure resulted in no further rise in intratubular or peritubular capillary pressure. Elevation of applied ureteral pressure in kidneys with collapsed tubules and in dead animals did not increase the intratubular pressure, demonstrating that the rise in intratubular pressure produced in this manner in functioning kidneys was not simply a direct back transmission of pressure. Elevation of renal venous pressure by compression of the renal vein also had no effect on intratubular and peritubular capillary pressures until their pre-existing values were exceeded, and then all three pressures rose together.
Changes in Myoglobin Content of the High Altitude Acclimatized Rat
Authors: Vaughan Burton E. , Pace Nello
Published: December 2017

A method is described for the assay of myoglobin in all myoglobin containing tissues of the rat, in particular the heart and diaphragm. Total body myoglobin increased 70% above sea level values, both in animals taken from sea level to 12,500 feet and in animals born and reared at 12,500 feet. In comparison with the muscle hemoglobin concentration increase of 50%, the blood hemoglobin concentration increased only 25% above sea level values. Whole body content of myoglobin was determined directly, and this amounted to 17.3 mg/100 gm of body weight, or to 42.3 mg/100 gm of wet muscle. Partition of the body myoglobin among seven muscle groups was ascertained. Heart, diaphragm and the two masseters contain only about 10% of the total myoglobin. Evaluation was made of the factors that have been suggested to explain the disparity in the originally reported myoglobin increases at high altitude of Hurtado et al. and more recent work. It is clear that failure to obtain the increase in the rat is attributable to the use of intermittent rather than continuous high altitude exposure. Evidence for full acclimatization in the animals here used was adduced. The suggestion is made that myoglobin maintains an optimal oxygen gradient between the cell plasma membrane and the mitochondria, and in so doing is involved in dynamic relation to cellular oxidation.
Inhibition by Barbiturates of Barium-Stimulated Intestinal Motility
Authors: Walker L. , Necheles H.
Published: December 2017

Following our demonstration that barium-stimulated intestinal activity could be depressed or inhibited with atropine, we have found that barbiturates had similar effects. In normal male and female mongrel dogs, anesthetized with chloralose-urethane, intestinal motility was stimulated by constant intravenous injection of BaCl2, and motility was registered by a balloon kymograph system. Nembutal, barbital and Amytal sodium, given intravenously, depressed motility of the small and large intestine in most instances, but the effects of the different barbiturates varied. It is concluded that barbiturates may depress cholinergic effects of barium, but also that they may depress smooth muscle directly.
Metabolic Activity of 3,3'-Diiodothyronine and 3,3'-Diiodo-5-Bromothyronine
Authors: Gemmill Chalmers L.
Published: December 2017

Following the preparation of (±) 3,3'-diiodothyronine and of (±) 3,3'-diiodo-5-bromothyronine, these compounds were tested for metabolic activity. It was found that 3,3'-diiodothyronine had only slight activity in the antigoiter test and in the oxygen consumption test in thyroidectomized rats. In contrast, (±) 3,3'-diiodo-5-bromothyronine had marked activity as compared with (–) 3,3',5-triiodothyronine. It is apparent from these results that iodine in position 5 is important for the activity of 3,3',5-triiodothyronine and it may be replaced by bromine with retention of metabolic activity.
Plasma, Extracellular and Muscle Electrolyte Responses to Acute Metabolic Acidosis
Authors: Tobin Richard B.
Published: December 2017

Nephrectomized cats were infused with hydrochloric acid in loads of from 3.5–9.6 mEq/kg. Extracellular moderation of the acidosis calculated from concentrations of electrolytes in plasma and inulin volumes of distribution was proportioned as follows: 35% by Na and 5% by K entering the ECS, and 20% by Cl and 24% by CO2 leaving the ECS. Calculated from changes in the chloride spaces, Na shift moderated 58%, CO2 22% and K 6% of the acid load. Sodium rather than potassium appeared to be the main extracellular moderator of acidosis under the conditions of these experiments. Direct muscle analyses showed a fall in intracellular Na and probably of K in response to extracellular acidosis. It is suggested that K i is not inversely related to extracellular ph. Calculated intracellular ph remained constant during the acidosis, indicating that cells may maintain a constant acid-base environment despite marked fluctuations of extracellular ph and that unmeasured mechanisms are responsible.
Metabolic Rate of Female Rats as a Function of Age and Body Size
Authors: Kleiber Max , Smith Arthur H. , Chernikoff Theodore N.
Published: December 2017

On the basis of 926 respiration trials, metabolic rates of normal female rats are presented as means of 42 different age groups from birth to 1000 days of age. The means with their standard errors are given for the metabolic rates per rat, per kilogram weight, per unit of the 2/3 power of body weight (surface), and per unit of the 3/4 power of body weight (inter specific unit of metabolic body size). A minimum of 72.6 Cal/kg.3/4 occurs between the ages of 200 and 300 days. An equation with two exponentials predicts the metabolic rate of rats from 77–1000 days of age with a standard deviation between prediction and observation of 2.2% of the mean.
Determination of Cell Volume in Massive Transfusions Using Fe59 and Cr51
Authors: Smith E. L. , Huggins R. A. , Kraintz L. , Seibert R. A. , Deavers S.
Published: December 2017

When dogs are injected with either or both Fe59 and Cr51-labeled cells (initial tag) prior to a series of transfusions (up to 20.0–25.0 cc % body weight) the measured blood and cell volume closely approach and may exceed the expected. After the series of transfusions are completed, if an additional isotope (final tag) is injected the blood and cell volumes are much less than the expected. The difference between the blood and cell volumes determined by the initial and final tag can be explained by the ‘trapping’ of red blood cells. The volume of red blood cells ‘trapped’ after multiple transfusion (up to 10.0–14.9% body weight) can equal or exceed the added cell volume.
Alkaline Phosphatase Activity in Various Mouse Tissues Following Total Body X-Irradiation
Authors: Mollura Joseph L. , Goldfeder Anna
Published: December 2017

The distribution of alkaline phosphatase in various mouse tissues (duodenum, spleen, liver, kidney and mammary glands) and the effects of ionizing radiation on the activity and distribution of this enzyme were studied by the use of the Gomori method. A total-body dose of 700 r, known to kill 50% of the mice of the C57/BL6 strain in about 9 days, as well as doses up to 10,000 r, failed to produce any apparent change in alkaline phosphatase activity of the various tissues which were removed from 2 hours to 14 days after exposure. On the basis of these observations it may be inferred that alkaline phosphatase is not involved in cytological damage induced by ionizing radiation.
Concentration of a Prothrombin Conversion Accelerator and Thrombin Precursor From Serum
Authors: McClaughry Robert I.
Published: December 2017

The method described by Seegers for obtaining purified prothrombin from plasma has been used for isolating a protein fraction from serum. The yields are about 20% as much protein from serum as from plasma. The serum product is a potent accelerator for the conversion of purified prothrombin to thrombin. Although the serum product contained very little prothrombin, as measured by quantitative two-stage analysis, thrombin could be obtained from it by activation in 25% sodium citrate solution. It is believed that the accelerator isolated from serum is a derivative of prothrombin.
Renal Arteriovenous Changes in Fructose and Blood Sugar in the Rat With Ligated Ureters
Authors: Reinecke Roger M.
Published: December 2017

A renal arteriovenous decrease in fructose occurs in both eviscerated and non eviscerated rats with ligated ureters that have been given an intravenous injection of fructose. It is accompanied by an equivalent or larger renal arteriovenous increase in the substances other than fructose that are measured as blood sugar by the reduction of alkaline ferricyanide in a tungstic acid filtrate of blood.
Effect of Acute Hyperthermia on Adrenal 17-Hydroxycorticosteroid Secretion in Dogs
Authors: Richards John B. , Egdahl Richard H.
Published: December 2017

Effect of acute hyperthermia on adrenocortical function has been studied by measuring 17-hydroxycorticosteroids in adrenal venous blood of anesthetized dogs. Dogs immersed to the shoulders in 50°C water respond initially with a rapid increase in rectal temperature (42°C in 15–20 min.), a marked (two to sevenfold) increase in adrenal corticoid output, and a slight (10–20%) increase in adrenal venous blood flow. When a rectal temperature of 44–45°C was attained, circulatory failure occurred and a concomitant decrease in adrenal corticoid output and venous blood flow ensued. Dogs subjected to a gradual increase in body temperature had increased adrenal 17-hydroxycorticosteroid secretion in the rectal temperature range of 39– 40°C, but this stimulatory response subsided as body temperature was further increased. Hypophysectomy abolished the adrenocortical response to hyperthermia, thus showing that the increased secretory activity of the adrenal cortex in hyperthermia is mediated via the pituitary gland.
Characteristics of the Somatic Afferent Projection to the Precentral Cortex in the Monkey
Authors: Kruger Lawrence
Published: December 2017

The afferent evoked electrical response in precentral and postcentral cerebral cortex was studied in anesthetized and unanesthetized monkeys. Responses to nerve volleys were obtained on both sides of the central sulcus, tactile evoked responses were limited to the contralateral postcentral gyrus. Precentral responses were evoked by stimulation of the fast cutaneous and slow muscle afferent fibers. The amplitude and distribution of precentral responses varied with the number of peripheral nerve fibers synchronously activated. The latency of precentral responses increased as a function of distance from the central sulcus. Precentral and postcentral potentials were altered in the same manner by topical application of Novocaine and strychnine and the spreading depression of Leão. The nature of the afferent precentral electrical response, the anesthetic conditions for its study and the possible functional role of this projection are discussed.
Early Hypotension Induced in the Rabbit by Whole Body X-Irradiation
Authors: Brooks Phillips M. , Gerstner Herbert B. , Smith Sidney A.
Published: December 2017

Two different experiments were performed. In the first, the aortic blood pressure and the respiratory chest movements were continuously recorded on 21 rabbits that received 630 r total body x-irradiation at a dose rate of 10.6 r/min. and these recordings were compared with those of 15 control animals. All irradiated rabbits showed a pronounced initial reaction characterized by severe hypotension and acceleration of respiratory rate. This reaction became noticeable in the second half of the irradiation period; in the majority of animals circulatory collapse with a mean pressure of 50 mm Hg or less developed during the first postirradiation hour. Thereafter, all rabbits began to recover from the collapse with the exception of four animals that died. In the second experiment, blood of 16 animals irradiated under the conditions of the first experiment was withdrawn during the collapse phase and the plasma lyophilized. In comparison with control plasma, the lyophilized irradiated material produced a slight but consistent fall in blood pressure when injected into nonirradiated test rabbits.
Effects of Anoxia on the Respiratory and Water Metabolism of Mouse Diaphragm
Authors: Hannon John P. , Cook S. F.
Published: December 2017

Alterations in the in vitro respiration and water metabolism of mouse diaphragm have been investigated following various intervals of in situ anoxia. There was first an increased respiratory rate when the period of anoxia was less than 20–30 minutes. A depressed respiratory rate was noted for periods greater than 20–30 minutes. The in vitro water content of mouse diaphragm was increased by prior exposure to anoxia. This increase occurred following as short an anoxia interval as 10 minutes and reached a maximum or plateau level when the exposure interval was about 60 minutes. The evidence strongly suggests an increase in intracellular osmotic concentration following anoxia.
Evidence for Increased Effectiveness of Placebos With Increased Stress
Authors: Beecher Henry K.
Published: December 2017

Evidence has been presented that placebos are increasingly effective with increased stress. This greater effectiveness seems to be dependent upon the greater significance of (reaction to) severe stress than less severe. Thus the concept of the importance of significance of symptoms in drug action is supported. It is possible that not only placebos but therapeutically effective drugs may also be proportionately more effective with increasing stress. It is believed that this is a new concept. The use of placebos in this study has made it possible to ascertain a) the importance of the reaction or processing phase in suffering, b) the effectiveness of drugs (placebos at least) as proportional to the significance and degree of the cause of the stress. Thus the use of placebos gives the means for attack on certain fundamental aspects of drug action.
Adrenal Steroids and the Liver in the Regulation of Peripheral Fat Mobilization
Authors: Tracht M. E. , Goldstein M. S. , Ramey E. R.
Published: December 2017

Changes in the fat content of the epididymal fat depot of the rat were used as a measure of the rate of peripheral fat mobilization during fasting and after phlorizin treatment in the adrenalectomized rat, and after fasting and muscle work in eviscerated rats. It was found that the adrenalectomized rat maintained on 1% saline did not differ from normal controls in its ability to mobilize body fat in response to fasting or phlorizinization. It appears that the inability of the adrenalectomized animal to develop a fatty liver is not due to inadequate mobilization of fat stores. Working, intact animals given glucose show an increased fat movement out of depot fat stores. The same degree of muscle work in the eviscerate rat, however, leads to a net increase in fat deposition in the epididymal fat body after 12 hours. It is suggested that the liver in some way regulates the movement of fat from storage areas in response to changes in the caloric needs of the animal.
Disparity Between Phenol Red and Diodrast Clearances in the Dog
Authors: Ochwadt Bruno K. , Pitts R. F.
Published: December 2017

The clearance of radioiodinated Diodrast and that of phenol red were compared in anesthetized dogs in an attempt to determine the reason why the former is roughly twice the latter, even though the two substances are secreted by the same mechanism. The infusion of sodium acetate increases both clearances but does not alter the ratio of the two. Hence availability of substrate is not likely to be a significant factor in restricting the clearance of phenol red relative to Diodrast. Replacement of plasma proteins, which bind phenol red, with dextran, which does not, increases the clearance of phenol red relative to Diodrast. This increase in clearance ratio is a result of an increase both in the quantity of dye filtered and in the quantity secreted. These experiments show that either rate of diffusion of free phenol red from peritubular capillaries into tubular cells or rate of dissociation of phenol red bound by plasma proteins is a limiting factor in secretory transport. However, the Diodrast clearance exceeds the phenol red clearance in isolated kidneys perfused with dextran solutions in which all dye is free. Thus, factors other than protein binding play some role in causing disparity of clearances.
Active Secretion in the Rabbit Oviduct
Authors: Bishop David W.
Published: December 2017

Determinations of the rates of secretion and the pressures against which ligated, catheterized oviducts of Dial-urethane-anesthetized rabbits produce tubal fluid indicate this to be an active secretion of the genital tract. Secretory activity is influenced by the hormonal condition of the animal. Both secretory rate and pressure are high during estrus (av., 0.79 ml/24 hr/tube and 46.0 cm H2O pressure) and low in late pregnancy (0.28 ml/24 hr/tube and 9.6 cm H2O pressure). Secretory activity is severely reduced after castration (0.14 ml/24 hr/tube and 11.8 cm H2O pressure), but this decrease can be counteracted by administration of estradiol benzoate (5 γ/day for 3 days). The secretory process is stimulated by pilocarpine (1.11 ml/24 hr/tube and 71.3 cm H2O pressure). The oviduct secretion may be considered to play a vital role in the reproductive economy of the rabbit.
Hormonal Influences on DDT Metabolism in the White Rat
Authors: Durham William F. , Cueto Cipriano , Hayes Wayland J.
Published: December 2017

The influence of diethylstilbestrol (DES) and testosterone propionate (TP) on the storage of DDT and its metabolite, DDE, was studied in normal and in gonadectomized rats. As expected, TP dosage increased the growth of female rats while DES administration inhibited the growth of males. Both hormones inhibited gonadal growth. Rats that received either DDT or hormone showed an increased liver weight/body weight ratio as compared to control animals. This effect was more marked in males than in females. DES increased DDT and DDE storage in fat in the male while TP decreased these values in the female. Similar effects of hormone dosage were noted on the ratio of DDE to total DDT-derived material stored in fat.