bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of mercurials on renal sulfhydryl and disulfide groups
Authors: Shore V. , Shore B.
Published: December 2017

Sulfhydryl and disulfide concentrations were determined amperometrically in homogenates and subcellular fractions of kidneys of normal rats and of rats injected with HgCl2, p-chloromercuribenzoate, or chlormerodrin. In normal kidney —SH greatly predominated. At 3 hr after injection of 3 mg HgCl2/kg or 7.3 mg chlormerodrin/kg, no significant increase in the concentration of renal —SS— was detected, although the —SS— reductase activity was greatly diminished by the injections. HgCl2 added in vitro to kidney homogenates in amount corresponding to less than 10% of the total —SH in the preparation also markedly inhibited the utilization of TPNH for reduction of —SS—. In kidneys removed at intervals between 6 and 24 hr after injection of HgCl2, chlormerodrin, or p-chloromercuribenzoate, increasing concentrations of —SS— with corresponding decreases in —SH concentrations were observed. These increases in —SS— are probably toxic manifestations most evident after diuresis has ceased, although physiologically significant changes in —SS— may occur earlier. Inhibition of —SS— reductase to a lesser extent than that observed with the doses of mercurials used might alter renal function with only small changes in —SS—/—SH, which are eventually overcome.
Stop flow studies of renal concentrating mechanism
Authors: Cooke C. Robert , Walker W. Gordon , Andrew David J. , Paulino Adoracion B.
Published: December 2017

Stop flow patterns of sodium, urea, and osmolality were obtained in dogs producing hypotonic urine following water loading, water loading plus urea, and water loading plus urea plus Pitressin. "Distal" and "proximal" peaks in osmolality, separated by a region where osmolality fell to or below free flow values, were regularly observed during water diuresis and water plus urea. The region of minimal osmolal concentration coincided with the distal region of minimal sodium concentration. In more proximal samples sodium concentration rose sharply above free flow levels to a maximum that coincided with and was adequate to account for the proximal osmolality peak. The proximal rise in osmolality, accompanied by a sharp rise in sodium concentration in the absence of a concomitant proximal rise in creatinine suggests re-entry of sodium into some proximal region of the nephron, probably the descending portion of Henle's loop. Urea showed a distal concentration rise but no proximal rise. Following Pitressin administration, the two osmolality peaks and the proximal sodium peak are obliterated and replaced by a single distal osmolality peak.
Tritiated bilirubin: preparation and physiological studies
Authors: Grodsky Gerold M. , Carbone John V. , Fanska Rudolph , Peng C. T.
Published: December 2017

A procedure is described for the preparation of tritiated bilirubin by the Wilzbach technique, either directly (preparation W) or in conjunction with irradiation from a Co60 source (preparation C-W). After equilibration of the preparations with polar and nonpolar solvents to remove labile tritium and repeated precipitation, the constant specific activities were 110 µc/mg (W) and 30 µc/mg (C-W), respectively. Radiochemical purity of the bilirubin-H3 preparations and their azobilirubin-H3 derivatives was demonstrated by paper chromatography. Bilirubin-H3 and a high dose of carrier bilirubin were injected simultaneously into rats and the comparative bilirubin levels in serum and bile were determined by radioactivity and colorimetric methods. After 75 min, 20–30% of the initial label remained in the serum as nonbilirubin radioactivity. Pre-equilibration in vitro of bilirubin-H3 with albumin removed the protein-labile tritium. It was concluded that the adsorption of bilirubin to serum protein may involve hydrogen binding at an aliphatic group on the bilirubin molecule. In serum and bile the distribution of the bilirubin-H3 (pre-equilibrated with albumin in vitro) was identical to the distribution of bilirubin measured colorimetrically. The half-life for disappearance of bilirubin from serum in these rats was 25–35 min.
Modification of intracranial self-stimulation by hunger satiety
Authors: Wilkinson Harold A. , Peele Talmage L.
Published: December 2017

The modifying effect of hunger satiety on intracranial electrical self-stimulation through implanted electrodes has been studied in cats. A feeding center was confirmed in the lateral hypothalamus in which self-stimulation was uniformly "positively rewarding." The positive-reward self-stimulation behavior so elicited was inhibited by prior feeding and was augmented by hunger— including postamygdalectomy hyperphagia. Self-stimulation in the rostral hypothalamic mating center was found not to be inhibited by feeding but to cause a decrease in subsequent food intake. Self-stimulation in other subcortical areas from which positive-reward behavior was elicited, both rostral and caudal to the above centers, was not affected by fasting-feeding. Stimulation in the ventromedial hypothalamic satiety center was uniformly "negatively rewarding."
Relationship of food and water intake in aurothioglucose obesity
Authors: Friedman Gerald , Waye Jerome D. , Janowitz Henry D.
Published: December 2017

After ld50 doses of aurothioglucose (ATG), extensive damage to hypothalamic structures other than those strictly involved in food intake has been demonstrated. The injury to areas previously shown to be concerned with the regulation of water intake prompted an investigation of the daily patterns of food and water intake in mice from the 2nd day after ATG injection for a period of 6 months. During the 1st month after ATG no statistically significant differences were noted in food or water intake or water-to-food ratios among mice destined to become obese, ATG-nonobese mice, or controls. From the 2nd to 6th month statistically significant increases in food and water intake were demonstrated among obese mice compared to ATG-nonobese and control mice. At no time after the injection of ATG was there a demonstrable difference in water-to-food ratios among the three groups. It is concluded that alteration of water intake regulatory mechanisms is not a concomitant of aurothioglucose obesity.
Effects of parathyroid extract. II: changes preceding renal calcification
Authors: Bradford Reagan H. , Howard R. Palmer , Joel Walter , Puls Jerry , Shetlar M. R.
Published: December 2017

Parathyroid extract, a total of 860 units, has been administered to rats in small, progressively increasing doses over a period of 12 days. The effects on serum protein, total glycoprotein, glycoprotein/protein ratio, calcium, individual protein and glycoprotein fractions, and renal calcification have been presented. Kidney sections from each rat were studied by histochemical techniques for calcification, neutral polysaccharide, and acid mucopolysaccharide. The serum total glycoprotein, glycoprotein/protein ratio, and calcium were found to be elevated. The serum albumin was decreased, whereas the globulin fractions were essentially unchanged. The globulin glycoprotein hexose, mostly α1-globulin, was increased; albumin glycoprotein hexose showed a somewhat less consistent increase. A "precalcification" periodic acid-Schiff-staining intraluminal material was demonstrated in the kidney after parathyroid extract treatment for 4 days. This was followed approximately 2 days later by Alcian blue-staining material and calcification demonstrable by hematoxylin and eosin and by Kóssa staining techniques. This has been interpreted as suggesting a glycoprotein-containing lesion which precedes calcification.
Effects of pentobarbital on temperature and heart rate of rats subjected to cold
Authors: Gemmill C. L. , Browning K. M.
Published: December 2017

A study at 5 C was made of body temperature and heart rate after a standard dose of sodium pentobarbital in normal, thyroidectomized, and hypermetabolic rats before and after subjection to 5 C for 46 hr. It was found that after subjection to cold in the normal rats, the body temperature and heart rate in some animals had more ability to recover after the barbiturate than in rats without previous exposure to cold. There was no ability to recover in the thyroidectomized animals either before or after subjection to cold. Most of the normal and thyroidectomized rats either with or without previous exposure to cold given sodium 3,3',5-l-triiodothyronine (T-3) had recoveries after the barbiturate. Some rats given T-3 and subjected to cold had a primary fall in temperature and heart rate that was followed by recovery and then a secondary fall.
Active transport of calcium by intestine: effects of hypophysectomy and growth hormone
Authors: Finkelstein James D. , Schachter David
Published: December 2017

The effects of hypophysectomy on active transport of calcium in vitro by everted gut sacs of rat duodenum are 1) an initial increase 4–5 days postoperatively and 2) a marked decrease 2–3 weeks postoperatively. The defect in transport results from reduction in the unidirectional transfers of Ca toward the serosa, and both steps in the transport (mucosal uptake and transfer to serosal surface) are impaired. Hypophysectomy also decreases iron transport (duodenal gut sacs), decreases l-proline transfer less strikingly (ileal gut sacs), increases d-galactose transport (jejunal gut sacs), and does not appear to influence either the electrical potential gradient from mucosa to serosa or the net flux of sodium. Treatment of hypophysectomized rats with a preparation of bovine growth hormone restores transfer mechanisms for calcium and iron. Ovine prolactin is also active in restoring the Ca mechanism, whereas other pituitary and nonpituitary hormones are not. Cortisone, l-thyroxin, and estradiol decrease Ca transport further in hypophysectomized rats. Absorption of Ca from loops of rat duodenum in vivo is also decreased 2 weeks after hypophysectomy and can be increased by prior treatment with bovine growth hormone.
Renal tubular secretion of o-acetylaminohippurate
Authors: Mudge Gilbert H. , Garlid Keith , Weiner I. M.
Published: December 2017

Renal tubular transport of o-acetylaminohippurate (OAAH) was investigated because of previous reports that it differed from other hippurates by not undergoing tubular secretion. However, tubular secretion was readily demonstrable in nine clearance experiments in dogs. Secretion was decreased by succinate, 2,4 DNP, probenecid, hippurate, and Diodrast, substances all known to inhibit secretion of other hippurates. In vivo deacetylation was demonstrated. In slice system of rabbit kidney cortex, accumulation was also shown, but degree of uptake was complicated by deacetylation to OAH. Meta and para isomers did not undergo deacetylation. Both in clearance studies and in kidney slices, the transport of OAAH is qualitatively similar to other hippurates.
Mammary gland cell content during various phases of lactation
Authors: Moon Richard C.
Published: December 2017

Deoxyribonucleic acid (DNA) was used as an index of the cellular state of the rat mammary gland in late pregnancy ( day 20) and early ( day 1), intense ( day 14), and declining ( day 28) lactation. Dams sacrificed on day 28 of lactation were provided with foster litters on day 14 postpartum to insure a strong sucking stimulus during the lactation period from days 14–28. Mammary DNA increased 57% from day 20 of pregnancy to lactation day 14, but no significant change in DNA content was evident by day 1 of lactation. A significantly lower DNA concentration was observed in mammary glands of rats sacrificed at lactation day 28 when compared with that of animals killed at day 14 of lactation. The data suggest that cellular proliferation of mammary gland continues well into lactation and that a decline in lactation may be due, in part, to a reduction in the number of milk-secreting cells.
Lipase activity of pigeon heart muscle particulate fractions and its metabolic significance
Authors: George J. C. , Iype P. Thomas
Published: December 2017

The lipase activity in the different particulate fractions of the pigeon heart muscle was determined manometrically. The microsomal fraction was found to have more of the enzyme activity than the mitochondrial one. The mitochondrial fraction was found to be incapable of oxidizing tributyrin and triolein in vitro. The possible role of the microsomes in the esterification of fatty acids and hydrolysis of fat is discussed.
Relation of renal amino and amide nitrogen extraction to ammonia production
Authors: Pitts R. F. , deHaas J. , Klein J.
Published: December 2017

In a series of ten experiments on dogs, net renal extraction of free amino acids and amides was compared with total renal production of ammonia. In acidosis, net extraction of amino and amide nitrogen accounts for 95% of ammonia production. In acute metabolic alkalosis, 80% of ammonia production can be so explained. However, in acute alkalosis superimposed on mild chronic alkalosis, only 11% of ammonia production can be related to amino and amide nitrogen extraction. These results suggest that in acidosis a steady state exists in which moment-to-moment extraction of amino acids and amides accounts for ammonia production. However, in acute alkalosis and especially in acute alkalosis superimposed on chronic alkalosis, nitrogen extraction is reduced disproportionately to ammonia production. For short periods of time intracellular stores of amino acids and amides can be utilized as precursors of ammonia. In confirmation of results of Van Slyke and colleagues ( J. Biol. Chem. 150: 481, 1943) we have observed that glutamine is the major precursor of ammonia.
Maternal behavior in the rabbit: endocrine factors involved in hair loosening
Authors: Farooq A. , Denenberg V. H. , Ross S. , Sawin P. B. , Zarrow M. X.
Published: December 2017

Evidence for the involvement of endocrine factors in the phenomenon of hair loosening is presented. A significant degree of hair loosening occurs on the day of nest building among pregnant and pseudopregnant rabbits. In the latter it occurs between the 19th and 21st day after the induction of pseudopregnancy; in the former it occurs toward the end of gestation. Progesterone administration toward the end of pregnancy significantly depressed the extent of hair loosening regardless of the occurrence of nest building. A significant degree of hair loosening could be induced in the castrated doe by treatment with a combination of estradiol, progesterone, and prolactin for 8 weeks. Hormone treatments of a shorter duration that induced nest building did not produce any hair loosening. Although nest building and hair loosening are correlated in time, the two phenomena can occur independently of each other and appear to be governed by separate mechanisms.
Increase of cerebral blood flow produced by low dosages of cyanide
Authors: Russek Mauricio , F. Adolfo Fernandez , Vega Cordelia
Published: December 2017

In cats and rabbits lightly anesthetized with pentobarbital or immobilized with Flaxedil and in encéphale isolé cats, the intravenous injection of NaCN in doses of 0.05 to 0.5 mg/kg produced a great increase in blood flow from the head (jugular vein) without any significant change in the blood flow from a hind limb (femoral vein). This would indicate that the increase in blood flow from the head was probably due to the brain and not to the nonnervous structures. This assumption was further supported by the large increase in the blood flow through the sagittal sinus. The greatest increase in jugular flow, threefold, was produced by 0.2–0.3 mg/kg of cyanide. This dose did not produce any significant change in the arterial, jugular, and femoral vein oxygen concentration, and hence in the A-V oxygen difference of head and limb. The results would indicate that the consumption of the brain is augmented by these dosages of cyanide.
Functional changes in ventricular muscle after crushing the sinoauricular node
Authors: Lewartowski Bohdan
Published: December 2017

The influence of changes of imposed rhythm and/or crushing of the sinoauricular node on the total cholinesterase activity and excitability cycle of the ventricular muscle has been investigated. Experiments were performed on rabbits anesthetized with chloralose (0.1 g/kg). A potentiometric titration method was applied for the estimation of cholinesterase activity. Acetylcholine bromide was used as a substrate. The strength-interval curves of the right ventricle driven in situ at various rates were recorded. Crushing the sinoauricular node was followed by a decrease in cholinesterase activity, if the heart was driven at a rhythm exceeding the spontaneou rate by 100 beats/min. Destruction of the node was followeds also by shortening of the absolute refractory period if the accelerated driving lasted for at least 20 min. It is supposed that the acetylcholine metabolism in rabbit ventricular muscle is influenced by the activity of the cardiac conductive system.
Digestion and mucosal absorption of fat in normal and bile-deficient dogs
Authors: Knoebel Leon K. , Ryan John M.
Published: December 2017

The role of bile in fat digestion and absorption was investigated by studying the intestinal intraluminar and mucosal cell changes which occur after feeding either cottonseed oil triglycerides or oleic acid to normal dogs and to dogs deprived of bile by cholecystonephrostomy. Although the intraluminar lipids of the bile-deficient dogs contained a higher than normal concentration of monoglycerides, lipolysis, as based on the high concentration of intraluminar free fatty acids, was quite extensive in the absence of bile and comparable to that obtained in normal dogs. The conclusion is that bile does not play an important intraluminar role in fat absorption associated with lipolysis. Mucosal lipid of dietary origin recovered after feeding either triglycerides or free fatty acids to normal dogs was primarily in the form of higher glycerides, whereas that recovered from the mucosa of bile-deficient dogs contained a larger than normal proportion of free fatty acids. This result suggests that the intracellular esterification of the absorbed products of fat digestion is retarded in the absence of bile.
Dynamic function of atrial contraction in regulation of cardiac performance
Authors: Brockman Stanley K.
Published: December 2017

Evidence has been obtained which demonstrates that atrial contraction consists of a peristaltic or wavelike contraction which propagates a pressure front toward the ventricle. When the pressure front reaches the ventricle, two events occur: 1) There is an atrial-induced rise in ventricular pressure along with an asynchrony in atrial and ventricular pressure which causes a negative difference in A-V pressure and closure of the A-V valve. 2) There is an atrial-induced rise in initial ventricular tension (end-diastolic pressure) and fiber length resulting in a marked augmentation of the ventricular response. By using the complete heart block preparation the atrial contribution to ventricular performance could be compared at an AS-VS interval in which it was maximum with an AS-VS interval in which there was no atrial contribution. The maximum increases in left ventricular performance were as follows: 12.2 cm H2O in end-diastolic pressure; 40% in fiber length; 25 mm Hg in aortic pressure; 27 ml in stroke volume; and 33 g-m in stroke work.
Skin temperature and blood flow in the rabbit ear
Authors: Honda N. , Carlson L. D. , Judy W. V.
Published: December 2017

The relation of skin temperature and blood flow in the rabbit ear may be expressed as (See PDF for Equation) where Ts is skin temperature, F is peripheral blood flow, TR is rectal temperature, Tr is room temperature, and K1, K2, K3, and α are constants. The constants vary with ambient temperature probably reflecting the degree of precooling that occurs in the circulating blood.
Behavior of uterine muscle in Na-deficient solutions; effects of oxytocin
Authors: Marshall Jean M.
Published: December 2017

Myometrial strips, from parturient or 21-day pregnant white rats, were exposed to Na-deficient solutions, and membrane potentials were recorded from single muscle fibers, isometric tension from the entire muscle strip. Reduction of [Na+]0 to 50% of normal had no observable effect on muscle activity. At [Na+]0 below this level, the amplitude and rising velocity of the action potentials declined and, below 10% of normal, muscle activity was abolished. The stimulatory action of oxytocin on the myometrium was unaffected by reductions in [Na+]0 down to 50% of the normal level. Oxytocin (50 µU/ml) stimulated the production of action potentials in muscles previously depressed by exposure to solutions containing 25% and 10% of normal [Na+]0. The data indicate that although the presence of sodium ions in the external solution is necessary for the production and maintenance of activity in uterine smooth muscle, certain quantitative differences exist between uterine muscle and skeletal or cardiac muscle regarding the relationship of membrane activity to [Na+]0.
Single proximal tubules of Necturus kidney. VIII: Na and K determinations by glass electrodes
Authors: Khuri Raja N. , Goldstein David A. , Maude David L. , Edmonds Charles , Solomon A. K.
Published: December 2017

Cation-sensitive glass electrodes have been used to measure Na and K concentrations in Necturus serum and in glomerular and proximal tubular fluid from Necturus kidney. It has been found that the ratio [Na]glomerulus/[Na]serum is 1.00 ± 0.02 and the ratio [Na]tubule/[Na]glomerulus is 0.99 ± 0.01 thus confirming previous measurements with the flame photometer which indicated that tubular Na concentration did not change as fluid moved along the proximal tubule in Necturus kidney. These results were also confirmed with cation electrodes placed in situ in the living animal. The K concentration in fluid collected from the most distal portion of the proximal tubule was found to be 1.8 ± 0.1 times more concentrated than that in the glomerulus, in agreement with a ratio of 1.6 ± 0.1 previously obtained on the basis of flame photometer measurements by Oken and Solomon.
Distribution of bilirubin-H3 in the fetal and maternal rat
Authors: Grodsky G. M. , Contopoulos A. N. , Fanska R. , Carbone J. V.
Published: December 2017

Bilirubin-H3 in maternal or fetal serum was injected in physiologic amounts into the jugular vein of 19- or 21-day-old fetal rats, and distribution of activity in fetal and maternal tissues was measured. Two hours after injection, 93–98% of the activity was recovered in whole fetal homogenates. Activity was not detectable in either maternal serum or liver, indicating less than 2.5% of the total dose was in either tissue. Approximately 1–4% of the total dose appeared in maternal bile. In other experiments, activity in fetal tissues, after correction for trapped serum bilirubin-H3, was: carcass 27%, serum 21%, liver 10%, and intestine 2.5%. Significant activity was detectable in lungs, brain, kidney, and stomach, and traces were noted in heart, placenta, umbilical vessels, and spleen. Based on rate of bilirubin secretion and synthesis in adult rats, fetal synthesis would be 2.5–10 times placental transfer. Results suggest that placental transfer of bilirubin or bilirubin metabolites may not completely explain the low levels of bilirubin found in fetal circulation but indicate that a slow rate of bilirubin production or increased bilirubin storage in fetal tissue are contributing factors.
Effect of strophanthidin on fluxes of potassium in rabbit kidney slices
Authors: Burg Maurice B. , Orloff Jack
Published: December 2017

The effect of the cardiotonic steroid strophanthidin on the K content and K42 exchange rates of rabbit kidney slices has been determined. Strophanthidin has been shown to decrease the influx of K into renal tubule cells, thereby accounting for an observed reduction in the K content of slices in vitro and a diminished rate of secretion of K in vivo. It is probable that the inhibitor also decreases the rate constant for efflux of K from the tubule cells. However, the latter conclusion requires qualification since the thickness and structure of kidney slices complicate the interpretation of isotope exchange data, particularly in this case with respect to the analysis of changes in K efflux.
Dynamic properties of denervated rat muscle treated with electrotherapy
Authors: Elliott D. R. , Thomson J. D.
Published: December 2017

Denervated rat gastrocnemii, compared with normal controls, showed slower shortening velocity and less shortening, performed less work, exhibited decreased values for Hill's constant a (shortening heat per centimeter shortening), a low P0 (maximum isometric tetanus tension) value and a higher a/P0 ratio, but showed no change in Hill's constant b (rate of extra energy released per gram tension decline from P0). Muscle not allowed to shorten during treatment ("isometric") showed greater shortening velocity than did denervated untreated muscle or muscle allowed to shorten freely during treatment ("isotonic"). Isotonically treated muscle showed a greater amount of shortening and a higher value for constant a than did denervated untreated or isometrically treated muscle, but no corresponding change in constant b. While isotonic treatment resulted in better maintenance of the amount of shortening and of the value for a than did isometric treatment, and isometric treatment resulted in better maintenance of velocity of shortening than did isotonic treatment, isometric treatment reduced constants a and b to values below those for denervated untreated muscle.
Effects of whole-body x-irradiation on electroshock seizure responses in developing rats
Authors: Vernadakis Antonia , Timiras Paola S.
Published: December 2017

Electroshock seizure responses were studied in control and irradiated rats between 8 and 55 days of age. Experimental animals were exposed to 500 r whole-body X-irradiation 2 days postnatally. In maturing rats seizure patterns produced by brain stimulation with 50 ma current appear in sequence: hyperkinesia, clonus, forelimb flexion, forelimb extension followed by hind limb flexion, and hind limb flexion followed by hind limb extension. In irradiated rats full flexor-extensor seizure pattern appeared in 50% of animals at 13 days of age, 3 days earlier than in controls. Extension was longer and flexion, clonus, and total seizure were shorter in irradiated than in controls. In both groups durations of clonus and total seizure were related inversely to durations of extension. Duration of flexion decreased and duration of extension increased up to 22nd day of age in all animals. This indicates increased neuronal activity as the brain matures. Also thresholds for minimal electroshock convulsions decreased up to 22nd day of age, further indicating increased brain activity with maturation. Thresholds were significantly lower in irradiated rats than in controls.
Effects of intense or prolonged stimulation on systole
Authors: Mazzella H.
Published: December 2017

The mechanical effects of prolonged and intense d-c pulses were studied in the toad heart. Both potentiation and depression of systole were observed, the result being, in general, dependent upon pulse polarity. The potentiation was markedly diminished in hearts from reserpinized and from sympathectomized animals, while the depressant effect was not susceptible to atropine. It is concluded that the inotropic actions of high-voltage pulses are mediated by two effects; one, as yet ill-defined, on the membrane excitation process and one by catecholamine release from the myocardium.
Effect of hypercalcemia on salivary secretion in the dog
Authors: Rothman Stephen S. , Brooks Frank P.
Published: December 2017

An attempt was made to ascertain the effects of an elevated serum calcium level on the rate of secretion and on the movement of sodium, potassium, chloride, bicarbonate, and calcium ions across gland cell membranes in the parotid and mixed glands of three chronic fistulous dogs. Pilocarpine HCl (.36 mg/kg) was injected intravenously to prime secretion and 45 min after the injection of pilocarpine, in the experimental studies, 5–10 ml of calcium gluconate was injected intravenously. Saliva was collected at 15-min intervals for 45 min after the calcium gluconate injection. An increase in the volume secreted, outputs, and concentrations of the ions were noted for the mixed glands during the first 15-min postcalcium injection. During the second 15-min postcalcium, the volumes secreted were significantly below control levels for both the parotid and the mixed gland preparations. Calcium output during the second 15-min postcalcium was decreased in comparison to control values for the parotid glands.
Mechanism of canine gastric hypersecretion after complete pancreatic ductal obstruction
Authors: Hein Michael F. , Silen William , Harper Harold A.
Published: December 2017

The effect of pancreatic enzymes (Viokase) on the gastric hypersecretion induced by pancreatic ductal ligation was studied in seven dogs with Heidenhain pouches. The pancreatic ducts were completely ligated after base-line determinations of the daily output of acid and secretory response of the pouches to histamine and tests of hepatic function. The influence on these tests of the preligation control diet and the following experimental diets was studied after the pancreatic duct ligation in varying sequence for 5–47 days: 1) control diet incubated with Viokase; 2) control diet mixed but not incubated with Viokase; 3) control diet incubated with heat-inactivated Viokase. Complete ligation of the pancreatic ducts was followed by marked gastric hypersecretion while the dogs were fed the control diet. Both the diet incubated with Viokase and the diet mixed with Viokase and then allowed to stand for 1–3 hr before feeding caused significant reduction of such hypersecretion. Evidence of hepatocellular damage was found after pancreatic ductal obstruction when active pancreatic enzymes were not added to the control diet.
Tidal volume, oxygen uptake, cardiac output, and body surface in the cat
Authors: Bartorelli Cesare , Gerola Augusto
Published: December 2017

Twenty-two cats were studied under chloralose anesthesia. When animals breathed pure oxygen in a closed circuit especially set for spirogram recording, respiratory rate, tidal volume, minute volume, and oxygen uptake of 19 cats averaged 15 breaths/min, 26 ml, 0.380 liter/min, and 18.5 ml/min, respectively. Cardiac output of 11 cats, determined by simultaneous measurements after Fick and Stewart-Hamilton methods, averaged 234 and 184 ml/min, respectively. Statistical analysis shows a high degree of individual variability partially dependent on body size. Body surface was directly measured in 12 animals and a coefficient for prediction of body surface on a body weight basis was calculated: m2 = 0.087 kg2/3. When corrected per unit of body surface, the range of individual oxygen uptake in 19 cats was reduced and it averaged 113/ml min m2. Similar correction of cardiac output was not equally effective.
Methionine and testosterone effect on occurrence of hemorrhagic diathesis in rats
Authors: Malhotra Om P. , Reber Elwood F.
Published: December 2017

Ninety orchiectomized rats were used to evaluate the effects of methionine and testosterone on the incidence of hemorrhages in animals fed a ration containing irradiated beef. Methionine significantly ( P < 0.01) decreased mortality linearly. Testosterone increased mortality linearly ( P < 0.01). The two substances acted independently. The protective effect of methionine was independent of growth. Omitting the aberrant mean value of prothrombin rate of 45 for 0.69%, dl-methionine and 1 mg testosterone from statistical analysis, only the linear effect of methionine is significant ( P < 0.01), amounting to about 10% increase in rate and, hence, a decrease of about 10% in prothrombin time for each 1% added dl-methionine. The per cent of plasma samples with prolonged prothrombin times had an aberrant point at the same location, and (omitting the aberrant datum) methionine decreased ( P < 0.01) the per cent prolonged prothrombin times, but testosterone had no significant effect. The body weight gain was significantly ( P < 0.01) greater for 0.69% than for 0 or 2.06% added dl- methionine.
Electroshock seizures and brain chemistry after acute exposure to moderate cold
Authors: Petschek Rodolfo , Timiras Paola S.
Published: December 2017

Adult male rats were exposed to 2.5 C for 60 hr, and responses to threshold and supramaximal electroshocks were studied. Body weights, adrenal and thymus weights, and concentrations of water, sodium, potassium, chloride, and glycogen (or glucose) in brain, liver, muscle, and plasma were determined. Cold exposure markedly lowered seizure threshold, but failed to affect the pattern of maximal seizures. It also caused a significant drop in body weight, as well as the adrenal hypertrophy and thymic involution usually observed under stress. Biochemical studies revealed brain (cortex, cerebellum, and brain stem studied separately) to be much more stable in water and electrolyte content than are liver, muscle, and plasma. Sodium retention in muscle and liver and potassium depletion in muscle occurred in the cold-exposed rats, probably as a result of increased secretion of mineralocorticoids, but these changes were not apparent in brain. Calculations of distribution of water and electrolytes in brain showed a significant increase in effective extracellular sodium in the cortex. Cold exposure caused hyperglycemia and a significant drop in glycogen content in all tissues analyzed.
Progressive changes in cardiovascular function after unilateral heart irradiation
Authors: Stone H. L. , Bishop V. S. , Guyton A. C.
Published: December 2017

Chronic heart failure was produced by giving 20,000 r Co60 irradiation to either the right or left ventricle in nine closed-chest animals. Measurements of right and left atrial pressures, arterial pressure, pulse rate, body weight, and blood volume were made before and after irradiation. The right and left atrial pressures rose progressively until death in three animals irradiated on the right side. In six animals irradiated on the left side, the left atrial pressure rose progressively, but the right atrial pressure either did not rise or rose only during the latter stages of failure. Declining arterial pressure and increasing pulse rate were common to both groups. Increases in blood volume were observed in all animals, but this increase was only significant in the group irradiated on the left side. At autopsy, 70–100% of the right ventricular muscle was damaged in dogs irradiated on the right side, and 40–70% of the left ventricle in dogs irradiated on the left side. Hydrothorax and liver congestion were found in the right-sided group and pulmonary congestion in the left-sided group.
Specificity of zinc pathway through the body: homeostatic considerations
Authors: Cotzias George C. , Papavasiliou Paul S.
Published: December 2017

Various tissues of the bodies of mice as well as various intracellular organelles of mouse liver cells showed distinct individuality relative to the time course of Zn65 distribution after intraperitoneal injection. When loss of Zn65 was accelerated by means of feeding of a zinc salt, the partition of this isotope among both organs and intracellular organelles remained unaffected. When, on the other hand, normal absorption was bypassed by intraperitoneal injection of a zinc salt, the distribution of Zn65 was perturbed. Thus it seems that the homeostatic controls discussed earlier ( Am. J. Physiol. 202:359, 1962) are operative over the entire zinc pathway only when the absorbtive and the excretory mechanisms are functioning together. Cadmium feeding, in contrast to zinc feeding, did influence the distribution of Zn65, as did also intraperitoneally administered cadmium. Cadmium feeding also induced an aberrant concentration of nondialyzable total nitrogen among the liver cell organelles.
Effect of changes in tidal ventilation on physiologic shunting
Authors: Hedley-Whyte J. , Laver M. B. , Bendixen H. H.
Published: December 2017

The rate and magnitude of the effects of the pressure-volume history of the lungs on the degree of physiologic shunting (pulmonary venous admixture) were investigated in 20 dogs, anesthetized and curarized. Atelectasis was promoted by decreasing end-expiratory transpulmonary pressure. Ventilation was with 100% oxygen using a constant-volume pump at a frequency of 20 breaths/min. The rates of increase or decrease in the physiologic shunt and of the gradients between derived alveolar oxygen tension and directly measured arterial oxygen tension (A-aD) showed a variation controlled by the pressure-volume history of the lungs. The physiologic shunts produced varied between 0.5% and 80% of the cardiac output. The interrelationships of the components of the shunt equation were studied and their relative value in predicting atelectasis was discussed. The data obtained were related to other observations made in anesthetized man.
Contractions of ventricular muscle in absence of certain cations
Authors: Nayler W. G. , Emery P. F.
Published: December 2017

The contractile activity of toad, lizard, and tortoise ventricles was investigated during perfusion with isotonic Ca++-free solutions containing sucrose, LiCl, and tetraethylammonium chloride instead of NaCl. In the absence of added Ca++ contractions were abolished by EDTA and by preliminary perfusion with modified Tyrode solution containing 100 mm Mg++. These findings are discussed in accordance with the hypothesis that Ca++ may be involved in the contractile activity of cardiac muscle perfused with Ca++-free solutions.
Beat-to-beat cardiovascular responses to rapid, low-level LBNP in humans
Authors: Hisdal Jonny , Toska Karin , Walløe Lars
Published: December 2017

The hypothesis tested was that there are significant transient changes in the cardiovascular variables after rapid onset and release of mild lower body negative pressure (LBNP, −20 mmHg), even in experimental situations where there is no detectable change in steady-state values. Twelve subjects participated in the study. Heart rate, stroke volume (SV), cardiac output, mean arterial pressure (MAP), total peripheral resistance (TPR), acral and nonacral skin blood flow, and blood flow velocity in the brachial artery were continuously recorded during the pre-LBNP period (0–120 s), during LBNP (120–420 s), and during the post-LBNP period (420–600 s). The main finding was that MAP is transiently but strongly affected by rapid changes in LBNP as small as −20 mmHg. There was also a characteristic asymmetry in cardiovascular responses to the onset and release of LBNP, particularly in the responses in SV. The transient changes in MAP indicate that the neural responses that affect TPR are not fast enough to compensate for the rapid changes in LBNP. In this case, the arterial baroreceptors will be activated as well as the low-pressure baroreceptors that sense central venous pressure. This must be taken into consideration in future discussions of the results of LBNP protocols.
Nitric oxide modulates renal sensory nerve fibers by mechanisms related to substance P receptor activation
Authors: Kopp Ulla C. , Cicha Michael Z. , Smith Lori A. , Hökfelt Tomas
Published: December 2017

Nerve terminals containing neuronal nitric oxide synthase (nNOS) are localized in the renal pelvic wall where the sensory nerves containing substance P and calcitonin gene-related peptide (CGRP) are found. We examined whether nNOS is colocalized with substance P and CGRP. All renal pelvic nerve fibers that contained nNOS-like immunoreactivity (-LI) also contained substance P-LI and CGRP-LI. In anesthetized rats, renal pelvic perfusion with the nNOS inhibitor S-methyl-l-thiocitrulline (l-SMTC, 20 μM) prolonged the afferent renal nerve activity (ARNA) response to a 3-min period of increased renal pelvic pressure from 5 ± 0.4 to 21 ± 2 min ( P < 0.01, n = 14). The magnitude of the ARNA response was unaffected byl-SMTC. Similar effects were produced by N ω-nitro-l-arginine methyl ester (l-NAME) but not d-NAME. Increasing renal pelvic pressure produced similar increases in renal pelvic release of substance P before and during l-SMTC, from 5.9 ± 1.4 to 13.6 ± 4.2 pg/min before and from 4.9 ± to 12.6 ± 2.7 pg/min during l-SMTC. l-SMTC also prolonged the ARNA response to renal pelvic perfusion with substance P (3 μM) from 1.2 ± 0.2 to 5.6 ± 1.1 min ( P < 0.01, n = 9) without affecting the magnitude of the ARNA response. In conclusion: activation of NO may function as an inhibitory neurotransmitter regulating the activation of renal mechanosensory nerve fibers by mechanisms related to activation of substance P receptors.
Factors that increase the contractile tone of the ductus arteriosus also regulate its anatomic remodeling
Authors: Kajino Hiroki , Chen Yao-Qi , Seidner Steven R. , Waleh Nahid , Mauray Françoise , Roman Christine , Chemtob Sylvain , Koch Cameron J. , Clyman Ronald I.
Published: December 2017

Permanent closure of the full-term newborn ductus arteriosus (DA) occurs only if profound hypoxia develops within the vessel wall during luminal obliteration. We used fetal and newborn baboons and lambs to determine why the immature DA fails to remodel after birth. When preterm newborns were kept in a normoxic range (PaO2: 50–90 mmHg), 86% still had a small patent DA on the sixth day after birth; in addition, the preterm DA wall was only mildly hypoxic and had only minimal remodeling. The postnatal increase in PaO2normally induces isometric contractile responses in rings of DA; however, the excessive inhibitory effects of endogenous prostaglandins and nitric oxide, coupled with a weaker intrinsic DA tone, make the preterm DA appear to have a smaller increment in tension in response to oxygen than the DA near term. We found that oxygen concentrations, beyond the normoxic range, produce an additional increase in tension in the preterm DA that is similar to the contractile response normally seen at term. We predicted that preterm newborns, kept at a higher PaO2, would have increased DA tone and would be more likely to obliterate their lumen. We found that preterm newborns, maintained at a PaO2>200 mmHg, had only a 14% incidence of patent DA. Even though DA constriction was due to elevated PaO2, obliteration of the lumen produced profound hypoxia of the DA wall and the same features of remodeling that were observed at term. DA wall hypoxia appears to be both necessary and sufficient to produce anatomic remodeling in preterm newborns.
The influence of nitric oxide synthase 1 on blood flow and interstitial nitric oxide in the kidney
Authors: Kakoki Masao , Zou Ai-Ping , Mattson David L.
Published: December 2017

The role of nitric oxide (NO) produced by NO synthase 1 (NOS1) in the renal vasculature remains undetermined. In the present study, we investigated the influence of systemic inhibition of NOS1 by intravenous administration of Nω-propyl-l-arginine (l-NPA; 1 mg · kg−1· h−1) and N5-(1-imino-3-butenyl)-l-ornithine (v-NIO; 1 mg · kg−1· h−1), highly selective NOS1 inhibitors, on renal cortical and medullary blood flow and interstitial NO concentration in Sprague-Dawley rats. Arterial blood pressure was significantly decreased by administration of both NOS1-selective inhibitors (−11 ± 1 mmHg with l-NPA and −7 ± 1 mmHg with v-NIO; n = 9/group). Laser-Doppler flowmetry experiments demonstrated that blood flow in the renal cortex and medulla was not significantly altered following administration of either NOS1-selective inhibitor. In contrast, the renal interstitial level of NO assessed by an in vivo microdialysis oxyhemoglobin-trapping technique was significantly decreased in both the renal cortex (by 36–42%) and medulla (by 32–40%) following administration of l-NPA ( n = 8) or v-NIO ( n = 8). Subsequent infusion of the nonspecific NOS inhibitor Nω-nitro-l-arginine methyl ester (l-NAME; 50 mg · kg−1· h−1) to rats pretreated with either of the NOS1-selective inhibitors significantly increased mean arterial pressure by 38–45 mmHg and significantly decreased cortical (25–29%) and medullary (37–43%) blood flow. In addition, l-NAME further decreased NO in the renal cortex (73–77%) and medulla (62–71%). To determine if a 40% decrease in NO could alter renal blood flow, a lower dose ofl-NAME (5 mg · kg−1· h−1; n = 8) was administered to a separate group of rats. The low dose of l-NAME reduced interstitial NO (cortex 39%, medulla 38%) and significantly decreased blood flow (cortex 23–24%, medulla 31–33%). These results suggest that NOS1 does not regulate basal blood flow in the renal cortex or medulla, despite the observation that a considerable portion of NO in the renal interstitial space appears to be produced by NOS1.
Central melanocortin system modulates energy intake and expenditure of obese and lean Zucker rats
Authors: Hwa Joyce J. , Ghibaudi Lorraine , Gao Jun , Parker Eric M.
Published: December 2017

Melanocortins play a critical role in appetite and body weight regulation, because manipulations of this pathway can lead to the development of obesity in several animal models. The purpose of this study was to use a melanocortin receptor agonist and antagonist to evaluate the involvement of melanocortins in feeding, energy metabolism, and body weight regulation in lean and obese Zucker rats. Central administration of a melanocortin receptor antagonist (SHU9119) elevated food intake and body weight of lean Zucker rats but had little effect in obese Zucker rats. In contrast, the melanocortin receptor agonist MTII reduced food intake in both lean and obese rats but was more potent in the obese Zucker rats. These data indicate the existence of functional melanocortin receptors in both lean and obese Zucker rats but suggest that obese Zucker rats have reduced endogenous melanocortin tone. In addition to its effects on food intake, MTII infusion elevated oxygen consumption and decreased respiratory quotient dose dependently during the light cycle. Our data suggest that a melanocortin receptor agonist can induce weight loss by increasing energy expenditure and promoting body fat utilization in addition to its inhibitory effects on food intake in both obese and lean Zucker rats.
Role of metabotropic glutamate receptors in vasopressin and oxytocin release
Authors: Morsette Delmore J. , Sidorowicz Hanna , Sladek Celia D.
Published: December 2017

The effect of metabotropic glutamate receptor (mGluR) activation on vasopressin (VP) and oxytocin (OT) release was evaluated using explants of the hypothalamoneurohypophysial system. (+/−)-1-Aminocyclopentane- trans-1,3-dicarboxylic acid (t-ACPD), an agonist at groups I and II mGluRs, increased VP and OT release in a concentration-dependent manner. A role for group I mGluRs in VP and OT release was demonstrated by the ability of a group I-specific mGluR antagonist, 1-aminoindan-1,5-idicarboxylic acid (AIDA), to block the effect of t-ACPD and the ability of a group I-specific agonist, ( R, S)-3,5-dihydroxyphenylglycine, to significantly increase both VP ( P = 0.0029) and OT ( P = 0.0032) release. However, AIDA did not alter VP or OT release induced by a ramp increase in osmolality of the perifusion medium. The role of group III mGluRs was examined using L(+)-2-amino-4-phosphonobutyric acid (L-AP4), an agonist of these receptors. L-AP4 did not change basal release of VP or OT and did not prevent osmotically stimulated hormone release. Thus mGluR activation stimulates VP and OT release, but it is not required for osmotic stimulation of hormone release.