bluuebunny/crossref_metadata_2025 huggingface dataset:
Gas transport by hemocyanin-containing blood of the Cephalopod Octopus dofleini
Authors: Lenfant Claude , Johansen Kjell
Published: December 2017

O2 and CO2 dissociation curves have been obtained for the hemocyanin-containing blood from the large Cephalopod, Octopus dofleini. The oxyhemocyanin curves showed a typical sigmoid shape. Values for T50 and T100 at 11 C and 0.4 mm Hg Pco2 were 15 and 70 mm Hg Po2, respectively. The amount of dissolved O2 in the blood at higher Po2 was considerable and could reach 10% of the total O2. The O2 capacity averaged 3.06 vol %. Dissolved carbon dioxide decreased the affinity of hemocyanin (Hcy) for O2 (Bohr effect) and reduced the O2 content at saturation (Root effect). At increased temperature the affinity to oxygen was decreased. The CO2 dissociation curves showed a moderate CO2-combining power. A distinct difference in CO2-combining power between oxygenated and reduced blood was present (Haldane effect). This difference was limited to the physiological range of Pco2. Increased temperature decreased the CO2-combining power. The buffering capacity of the blood was low, but in the physiological range of pH there was a distinct difference in buffering ability between reduced and oxygenated blood. The findings are discussed in relation to other marine animals.
Effect of extracellular pH on function and metabolism of isolated perfused rat heart
Authors: Opie Lionel H.
Published: December 2017

The extracellular pH of the isolated perfused rat heart was varied from 6.9 to 8.0 usually by altering the bicarbonate content of the buffer. Isovolumic left ventricular contractility was measured by an intraventricular balloon. The peak systolic pressure was dependent on the coronary flow rate. At a constant flow rate the peak pressure and cardiac rate were unchanged at 7.4–8.0 but declined at about pH 7.1. The uptake and fate of pyruvate-1-C14 (6 mm) and palmitate-1-C14 (0.7 mm) were similar at pH 7.1–8.0. Compared with pH 7.4, oxidation rates of glucose-U-C14 (5 mm) and acetate-2-C14 (5 mm) were unchanged at pH 7.1, but were greater at pH 8.0. Other increases at pH 8.0 (glucose 5 mm) were in glucose uptake, lactate and pyruvate formation, and the percentage of the glucose uptake accounted for by the sum of C14O2, lactate, and pyruvate formed. It is concluded that in spite of decreased mechanical activity at pH 7.1, Krebs cycle activity is unaltered by pH changes from 7.1 to 8.0, whereas glycolysis and acetate oxidation increase above pH 7.4.
Training and bradycardia in rats
Authors: Tipton Charles M.
Published: December 2017

Bradycardia produced by training was investigated in 228 mature male rats belonging to normal, vagotomized, diencephalon-lesioned, immunological sympathectomized, and hypophysectomized groups. During a 70-day experimental period, resting heart rates of trained unanesthetized rats were significantly lower than those of non-trained rats at approximately 40 days after the training program had been initiated. Resting heart rates were correlated with body weight, wet and dry heart weight, percentage of solids, and the heart weight/body weight ratio (heart ratio). Several coefficients were statistically significant but the majority of the coefficients were below ±0.60 and exhibited a low relationship between the various parameters. Heart ratios for the trained vagotomized, diencephalon-lesioned, and immunological sympathectomized were significantly lower than the ratios from normal trained animals. Similar trends were observed with the nontrained subgroups when these ratios were compared with normal nontrained animals. The only exercising group that exhibited statistical evidence for cardiac hypertrophy was the normal trained group. It was concluded that other aspects beside the weight of the heart must be considered in any satisfactory explanation for this form of bradycardia.
Mechanism of reactive hyperemia in limbs of anesthetized dogs
Authors: Kontos Hermes A. , Mauck H. Page , Patterson John L.
Published: December 2017

Reactive hyperemia was studied in the hindlimb and forelimb of 81 anesthetized dogs. Reactive hyperemia volume in response to 5-sec arterial occlusions correlated moderately well with the decrease in intravascular pressure. This correlation was poor for 30-sec arterial occlusions. Venous congestion induced by venous occlusion decreased or abolished the vasodilator response to 5-sec arterial occlusions and decreased the response to 30-sec occlusions. Evidence is presented supporting the view that this effect of venous congestion was related to reduction in the fall in intravascular pressure during arterial occlusion. The response to 30-sec occlusions was decreased during acutely induced hypocapnia and increased following acetazolamide administration. The data support the view that both physical and metabolic factors contribute to the production of reactive hyperemia. They further suggest that the accumulation of CO2 in the ischemic tissues contributes to the production of reactive hyperemia.
Effect of acute carotid arterial constriction on aldosterone secretion in dogs
Authors: Davis James O. , Olichney Michael J. , Brown Torrey C. , Binnion Peter F. , Urquhart John , Higgins James T.
Published: December 2017

Steroid secretion was studied during acute carotid arterial constriction and subsequently after exogenous ACTH injection in anesthetized animals with a chronic indwelling adrenal venous catheter. Aldosterone secretion increased during carotid constriction in only four of nine experiments. In one animal, the increment in aldosterone output was associated with an increase in adrenal blood flow. In the other three experiments the increase in aldosterone output appeared to be secondary to an elevation in circulating ACTH as indicated by simultaneous increments in corticosterone and cortisol secretion. A striking increase in secretion of all three steroids occurred following the subsequent administration of 100 mU ACTH. No evidence was obtained to indicate that carotid constriction augments aldosterone output by activation of a central nervous mechanism except via ACTH release.
Lactate concentration in the medulla of rat kidney
Authors: Scaglione Peter R. , Dell Ralph B. , Winters Robert W.
Published: December 2017

In vitro studies by others have shown that the inner medulla of the mammalian kidney, site of the countercurrent system for urine concentration, is a tissue capable of supporting anaerobic glycolysis at high ambient osmolalities. In vivo, this region of the kidney is believed to be relatively poorly supplied with oxygen, raising the possibility that glycolysis may provide energy for maintenance of the countercurrent system. Accordingly, lactate and sodium concentrations were measured in the inner medulla of the rat kidney under varying conditions of urine flow and osmolality. Osmotic diuresis, but not water diuresis, was associated with a twofold rise in inner medullary lactate compared to antidiuretic controls. Serum and renal cortical lactate levels were unaffected. Medullary sodium fell significantly during osmotic diuresis only. These results suggest that the transport of sodium in the loop of Henle may be linked to glycolytic metabolic pathways responsible for the high amount of lactate found in the inner medulla of mammalian kidney.
Kinetics of ammonia production and excretion in the acidotic dog
Authors: Fulgraff Georges , Pitts Robert F.
Published: December 2017

The Chinard technique of rapid injection into one renal artery of a glomerular marker (creatinine) and a compound whose utilization or excretion is under investigation has been employed in a study of the time courses of production and excretion of ammonia. Following the injection of N15H4 Cl or amide-N15-labeled glutamine, the label appeared in the urinary ammonia within a partially corrected time interval of 11 sec or less, suggesting that, in both instances, the labeled ammonia entered the urine as far along the nephron as the convoluted portion of distal tubules and cortical collecting ducts. Creatinine appeared in the urine after a delay of 60–100 sec. Following injections of amino-N15-labeled glutamine, appearance of label in urinary ammonia was delayed about 20 sec relative to that observed following injection of amide-N15-labeled glutamine. The time course of disappearance of label from the urine suggests that deamidation of glutamine is not rate-limiting for ammonia production and excretion, whereas deamination of glutamine may well be.
Electrical transmission of slow waves from longitudinal to circular intestinal muscle
Authors: Bortoff Alex
Published: December 2017

Circular muscle from cat intestine exhibits spontaneous rhythmical contractions only when it is attached to longitudinal muscle. Under these conditions electrical slow waves can be recorded from circular muscle, but they disappear following complete removal of the longitudinal layer. If a small patch of longitudinal muscle remains, slow waves can be recorded from adjacent circular muscle. Those recorded lateral to the longitudinal layer are synchronized with slow waves recorded directly from this layer. Their amplitude decreases exponentially with distance, approaching zero at about 12 mm from the lateral edges and about 3 mm from the oral or aboral edge of the longitudinal layer. Slow waves can also be recorded across the entire intestinal wall or across a longitudinal-circular muscle preparation. With this method of recording, the amplitude of the slow waves decreases as the thickness of the circular layer is reduced by stripping away its innermost layers. The amplitude is not increased by replacing these layers. These results indicate that slow waves may be transmitted electrotonically from longitudinal to circular muscle, implying the existence of electrical continuity between the two muscle layers. The transmission of slow waves can account for the coordinated spontaneous rhythmicity exhibited by circular muscle under normal conditions, i.e., when attached to the longitudinal layer.
Effect of acute coronary occlusion on myocardial nutritional circulation in swine
Authors: Howe B. B. , Winbury M. M.
Published: December 2017

Page 1069: B. B. Howe and M. M. Winbury, "Effect of acute coronary occlusion on myocardial nutritional circulation in swine." Page 1071: figures 2 and 3 should be reversed.
Synthesis of serine by the dog kidney
Authors: Pitts R. F. , MacLeod M. B.
Published: December 2017

Page 394: R. F. Pitts and M. B. Macleod. "Synthesis of serine by the dog kidney." Page 396, column 1 and page 397, column 1, the figure labeled Fig. 2 is Fig. 3; the figure labeled Fig. 3 is Fig. 2. The legends are correct.
Influence of food deprivation and adrenal steroids on DNA synthesis in various mammalian tissues
Authors: Goldberg AL , Goldspink DF
Published: December 2017

The DNA content of skeletal muscle increases as young rats grow. Food deprivation prevented this increase: total DNA remained constant, while muscle weight and RNA decreased. Diaphragms isolated from fasted rats incorporated [3H]thymidine into DNA far more slowly than tissues from fed rats. Incorporation returned to control levels on refeeding. Fasting for 24 or 48 h also markedly reduced [3H]thymidine incorporation by slices of liver, kidney, and brain. The factors responsible for this inhibition of DNA synthesis were investigated. Amino acids, insulin, or serum from fed or fasted rats failed to alter thymidine incorporation by muscle. Injection of hydrocortisone into normal rats reduced incorporation into kidneys, liver, and muscle within 4h. Incubation of hemidiaphragms with hydrocortisone suppressed [3H]thymidine incorporation within 2-3h. Adrenalectomy enhanced incorporation into DNA by diaphragm, liver, kidney, and brain. When fasted, adrenalectomized rats showed little or no suppression of [3H]thymidine incorporation and lost less weight than fasted controls. These data suggest that adrenal steroids are important in inhibiting DNA synthesis during normal growth and during fasting.
Changes of sodium transport in erythrocytes of the maturing rabbit
Authors: Smith EK , Weihrauch L , Farrington D
Published: December 2017

The red blood cells of New Zealand white rabbits have a low sodium and high potassium content. As the animals mature, the sodium concentration rises and the potassium content falls; studies of red cells from a group of five young and five mature animals revealed a highly significant increase of cell sodium with age that was associated with a significant fall in the rate of ouabain-inhibited active sodium efflux. This difference was still seen when the sodium concentration within the cells from old and young animals was equalized and elevated to saturating levels for active pump efflux. Total sodium efflux, however, increased significantly with age as did total sodium influx so that a steady state was reached. Ouabain-sensitive ATPase activity fell significantly in the cell membranes from older animals and ouabain-insensitive ATPase increased with age. The survival time of 51Cr-labeled red cells was significantly longer in old than in young animals and it is concluded that as the rabbit matures its red cells survive for a longer period and this is associated with the changes of sodium transport and ATPase activity that have been documented.
Nature of aortic smooth muscle responses to changes in venous return in intact dogs
Authors: Nicolosi GR , Pieper HP
Published: December 2017

A response of the aortic smooth muscle to reduction in venous return was demonstrated previously. The present experiments were performed to determine whether these responses were of a reflex origin rather than being attributable to viscoelastic mechanisms. Viscoelastic mechanisms could not account for changes seen in the aortic pressure diameter relationship curve. On the other hand, it was demonstrated that the response was abolished by eliminating sympathetic input to the aorta via spinal cord transection. This and other evidence demonstrate beyond doubt that the aortic response to reduction in venous return is of neurogenic origin and constitutes a well-integrated reflex. However, experimental evidence is presented which clearly indicates that the receptors for the aortic smooth muscle response are not located in either the carotid sinus or aortic arch but must be located elsewhere in the system.
Nonelectrolyte permeability of the paracellular pathway in Necturus proximal tubule
Authors: Berry CA , Boulpaep EL
Published: December 2017

Micropuncture experiments were performed on Necturus proximal tubule using stationary microperfusion and microrecollection techniques. The transepithelial movement of the extracellular marker, sucrose, was used to investigate the passive permeability of the paracellular shunt pathway under steady-state conditions, during spontaneous reabsorption and water flow induced by an external osmotic gradient. Measurements were made of the sucrose permeability (P-s) efflux, net flux, and of net volume flow. True P-s determined in the absence of net volume flow and transepithelial gradient was 0.96 10-6 cm s-1. Both ouabain and isotonic volume expansion decreased shunt P-s. During reabsorption, solute-coupled water flow increased apparent P-s and net sucrose flux equalled efflux. Osmotic water flow from lumen to plasma decreased apparent P-s, with net sucrose flux equal to efflux; whereas osmotic flow from plasma to lumen increased apparent P-s but no net flux was observed. It is concluded that changes in P-s can be interpreted as relative alterations of the tight junction and the lateral spaces and that a portion of the volume flow from lumen to plasma proceeds via the tight junction.
An effect of hyposmolarity on insulin release in vitro
Authors: Blackard WG , Kikuchi M , Rabinovitch A , Renold AE
Published: December 2017

An abrupt reduction of medium osmolarity by as little as 20 mosM evoked a discrete short-lived insulin secretory response from perifused chopped pancreas or isolated islets. The insulin response occurred earlier than that induced by either glucose or tolbutamide. None of the usual modifiers of insulin secretion significantly altered this secretory response. Glycolytic inhibitors, adrenergic agonists and blocking agents, cholinergic blocking agents, mitotic spindle inhibitors, and agents influencing sodium pump activity failed to alter hyposmolar-induced insulin secretion. Manipulation of the perifusion medium calcium concentration was the only procedure tested that influenced the secretory response. Perturbations of medium calcium concentration that increased the tissue-to-medium calcium gradient augmented the hyposmolar-induced insulin response and those that decreased tissue-to-medium calcium gradient greatly inhibited the response. The precise cause of the insulin response to a decrease in bathing fluid osmolarity remains undefined; however, the stimulus is not specific for insulin because increases in glucagon and amylase were also elicited by the hyposmolar stimulus.
Effect of osmolarity on intracellular pH of rat diaphragm muscle.?22
Authors: Adler S , Anderson B , Zett B
Published: December 2017

To investigate the effect of altered extracellular osmolarity on cell pH, intact rat diaphragms were incubated in a Krebs-Ringer bicarbonate solution. Cell pH was measured simultaneously by weak-acid (pH DMO) or weak-base (ph nicotine) distribution. When osmolarity was raised by mannitol addition, cell water decreased 5-10% (P smaller than .01) while both pH DMO and pH nicotine increased (P smaller than .01) under acid, normal, and alkaline external pH conditions. Hyperosmolarity of identical degree caused by urea resulted in no changes in either cell water or cell pH. Identical amounts of mannitol added to the bath in the absence of external osmolar changes resulted in no changes in either cell water or cell pH. When extracellular osmolarity was lowered by decreasing sodium chloride concentration, cell water increased 10-12% (P smaller than .01). Despite this large change in cell water, no changes in pH DMO or pH nicotine occurred. These data indicate that osmolar induced alterations in cell water only partially explain cell pH changes found in abnormal osmolar states. Alterations in passive and active hydrogen ion transport must also play significant roles.
Distal permeability to urate and effects of benzofuran derivatives in the rat kidney
Authors: Kramp RA , Lenoir R
Published: December 2017

Effects of benziodarone and benzbromarone on renal tubular permeability to urate-14C were investigated in anesthetized rats by microinjection and clearance experiments. Urate-14C and inulin-3H were injected into proximal and distal convolutions and their recovery was measured in urine collected serially. In control rats, total and direct recoveries were significantly lower after early proximal (72 and 52%, respectively) than after late proximal injections (83 and 63%), whereas distal recoveries were higher (94 and 69%). Delayed excretion (ca. 25%) did not change with site of injection. Total distal recoveries were always less than 100% (P smaller than 0.001) but increased to 98% at high loads. After proximal injections in drug-pretreated rats, total and direct recoveries increased significantly (P smaller than 0.001). Recoveries after distal injections did not change in benzbromarone-treated rats, whereas direct and delayed excretion, respectively, increased (87%) and decreased (9%) significantly (P smaller than 0.001) following benziodarone infusion. These findings demonstrate inhibition of proximal urate reabsorption by benzofuran derivatives. The results also suggest distal reabsorption of urate, presumably along the collecting ducts.
Relation between length, isometric force, and O2 consumption rate in vascular smooth muscle
Authors: Paul RJ , Peterson JW
Published: December 2017

The length-tension and length-oxygen consumption rate relationships were studied in bovine mesenteric vein at 37 degrees C. The absence of spontaneous mechanical activity permits straightforward interpretation in terms of active (smooth muscle) and passive components of the vein wall. Longitudinal loops, the predominant smooth muscle component being oriented in the longitudinal (axial) direction, were maximally stimulated using epinephrine (2-5 mug-ml-1). An optimum length for isometric tension development was exhibited at which the passive tension was 25% of the total tension. The population regression indicated that tension was developed at lengths which ranged from 0.33 to 1.41 times the length at which maximum tension was developed. Oxygen consumption was measured using a Clark-type polarographic electrode. Basal oxygen consumption was 0.432 plus or minus 0.014 (n equal to 121) mumol-min-1 (g dry wt)-1. The basal rate was found to be independent of the passive tension. Under conditions of maximal stimulation, the oxygen consumption rate at L-o, the resting length at which the tissue maintained 1 g-wt passive tension, was approximately twice the basal rate. The length dependence of the suprabasal oxygen consumption was parallel to that of the active isometric force. This parallel relation reflected a linear relation between active isometric force (deltaP-o) and suprabasal oxygen consumption rate (deltaJ-o2). The slope of the deltaJ-o2-deltaP-o linear regression was 0.142 plus or minus 0.013 nmol O2-MIN-1 (G-WT-CM)-1. DeltaJ-o2 at the minimum contracted length, at which no active force was developed, was 15-20% of the deltaJ-o2 measured when maximum isometric force was developed. This provides an upper bound to the rate of chemical energy utilization required for activation processes. The length dependence of active isometric force and chemical energy utilization is most simply interpreted in terms of a sliding-filament model.
Respiratory fluctuations in pupil size
Authors: Borgdorff P
Published: December 2017

Regular fluctuations in pupil size of the cat were measured and the properties, nervous pathways, and origin of these oscillations were investigated. The rhythm of pupil movements under control conditions appeared to be either locked to the central respiratory cycle or to the artificial ventilatory cycle. These movements were only seen in lightly anesthetized or tranquilized cats, but not in alert or deeply anesthetized cats (ether, halothane or pentobarbital). The fluctuations proved to be independent of sympathetic innervation but related to variations in parasympathetic outflow. At least two sources for pupil oscillations appeared to be involved: central respiratory activity and respiratory blood pressure fluctuations that modulated pupil width via sinoaortic baroreceptors. Lung movements per se, as a third possible factor, did not modulate pupil width, whereas electrical stimulation of the afferent lung vagi did; therefore the role of this mechanical factor is not clear. A review of the pertinent literature shows that in the organism there are many phenomena exhibiting respiratory oscillations. It seems likely that these oscillations have the same origin as the respiratory pupil fluctuations.
Distribution of H+ and HCO3 minus between CSF and blood during respiratory alkalosis in dogs
Authors: Hornbein TF , Pavlin EG
Published: December 2017

Anesthetized, paralyzed dogs after a control period at normal pHa were hyperventilated to produce a hypocapnic alkalosis. The pH, PCO2, (HCO3 minus), and (lactate) in cisternal and lumbar CSF and arterial blood were determined at normal conditions (control) shortly after induction of respiratory alkalosis (time 0) and 3, 4.5, and 6 h thereafter. These values along with measurements of the CSF/plasma DC potential (E) allowed calculations of the electrochemical potential difference (mu) between CSF and blood for H+ and HCO3 minus. After 6 h of hypocapnic alkalosis, muH+ and muHCO3 minus had returned to minus 0.7 and minus 1.0 mV of control at the cistern and to minus 1.0 and +0.4 mV of control for lumbar CSF. This return of mu is compatible with a passive distribution of these ions though active ion regulation is not ruled out. Assuming passive distribution, differences in deltaE/DELTApHa between metabolic and respiratory acid-base changes determined the extent of CSF pH homeostasis during compensated acid-base derangements.
Insulin and epinephrine effects on heart glycogen synthase and phosphorylase activity
Authors: Nuttall FQ , Gannon MC , Bergstrom WJ
Published: December 2017

The effect of intravenous epinephrine on heart glycogen synthase and phosphorylase systems in control and insulin-pretreated rats was studied. The percent of synthase in the I form decreased rapidly after epinephrine treatment but the change was small and sometimes not significant. In insulin-pretreated rats in which the percent synthase I was increased, epinephrine produced a definate and highly significant decrease. There was a simultaneous increase in percent phosphorylase a in both groups. The synthase and phosphorylase responses were statiscally significant at 2.5 mug epinephrine/kgor more. These data are compatible with a mechanism in which protein kinase is activated by an increased cAMP concentration and affects both the synthase and phosphorylasesystems simultaneously. Propranolol blocked the epinephrine effects on cAMP, synthase I, and phosphorylase a. Although insulin had little effect on the response ofthe synthase and phosphorylase systems to epinephrine, it nealry completely blocked glycogen degradation. The mechanism is unknown, but it appears to be due to an inhibition of phosphorylase a catalytic activity in vivo. Acetylcholine had no effect on synthase I, phosphorylase a, or cAMP in control or in insulin-pretreated animals.
Effect of hyperventilation on dynamics of cerebral energy metabolism
Authors: Kogure K , Busto R , Matsumoto A , Scheinberg P , Reinmuth OM
Published: December 2017

Hypocapnia of moderate and extreme degree (Paco2 21.1 and 13.5 torr, respectively)was induced by hyperventilation in rats subjected to the closed system of Lowry inorder to evaluate the effects on utilization rate of cerebral energy metabolites. The tissue levels of high-energy phosphates and calculated intracellular pH did not change, whereas glucose, pyruvate, and lactate increased significantly. The La/Pyratio and NADH/NAD-+ RATIO BOTH INCREASED IN PROPORTION TO THE DEGREE OF HYPOCAPNIA.Utilization rates of glucose, glycogen, and ATP were all significantly reduced by hypocapnia, whereas the utilization rate of phosphocreatine was increased. The rate oftotal high-energy phosphate use was also diminished in proportion to the degree of hypocapnia. The constant value of the energy charge (0.94 plus or minus 0.01) indicates that the energy production rate might also be reduced by hyperventilation; thus the intermediate metabolics and substrates increased. It is concluded that extreme hypocapnia reduces the rate of cerebral energy metabolism significantly.
Bilirubin UDP-glucuronyltransferase activity of wistar rat kidney
Authors: Foliot A , Christoforov B , Petite JP , Etienne JP , Housset E , Dubois M
Published: December 2017

Wistar rat kidneys have been shown to possess a bilirubin glucuronyltransferase (BGT) activity capable of conjugating about 3/5 of the total pool of unconjugated bilirubin within 48 h of being grafted to Gunn rat hosts. Bilirubin conjugated by the kidney is taken up by the liver and excreted in the bile. Except when the bile duct is ligated, no conjugated bilirubin appears in the plasma or urine. Renal BGT activity is about 1/20th of the hepatic activity on a weight basis in Wistar rats. The Gunn rat's hyperbilirubinemia probably causes an induction of the renal enzyme since its activity doubles in 48 h.
High-output heart failure in the dog: systemic and intrarenal role of angiotensin II
Authors: Freeman RH , Davis JO , Spielman WS , Lohmeier TE
Published: December 2017

Dogs with experimental high-output heart failure (HOF) exhibit marked retention of salt and water secondary to hypersecretion of both renin and aldosterone. The present study was undertaken to evaluate the systemic and intrarenal arteriolar action of angiotensin II (AII) in dogs with HOF and to provide additional information about the role of AII in low-output states. The intravenous infusion of a specific AII antagonist, [Sar1, Ala8]AII (6 mug/kg min-1), into conscious dogs with HOF decreased the mean arterial pressure (AP) from 101 +/- 7 to 83 +/- 7 mmHg (P less than 0.01) after 45 min of infusion. Intrarenal arterial infusion of the AII antagonist (0.2 and 2.0 mug/kg min-1) into anesthetized dogs with HOF also decreased AP and produced a marked increase in renal blood flow (RBF) with no changes in either creatinine clearance or sodium excretion. Similar results were obtained during the intrarenal infusion of the antagonist into sodium-depleted dogs and dogs with thoracic vena caval constriction, but not in normal dogs. The data demonstrate an important role for AII in the regulation of AP and RBF in high- and low-output states.
Hydrogen ion transport in the rabbit esophagus
Authors: Chung RS , Magri J , DenBesten L
Published: December 2017

The lumen of the rabbit esophagus was perfused in vivo with solutions (one solution per esophagus) containing 0-160 mM HCl by a constant circulation technique for 5 h. During the 1st h, net H+ flux out of the lumen (efflux) was minimal at H+ concentrations of 80 mM or less, but increased linearly with increase in luminal H+ concentrations above 80 mM. After 3 h, the net H+ efflux increased proprtionately to increasing H+ concentrations above a threshold of 20 mM. At the 5th h a linear relationship between net H+ efflux and luminal concentration was seen at all concentrations. Histological damage accompanied increase in H+ efflux and correlated with luminal acid concentrations and duration of exposure. We conclude that the rabbit esophageal mucosa is essentially impermeable to H+ below a threshold concentration of 80 mM for up to 1 h of exposure. When exposure is prolonged, this threshold steadily decreases with time. The occurrence of passive H+ diffusion above threshold concentrations most probably results from an increase in mucosal permeability, possibly an initiating event in the genesis of esophagitis.
Satiety and hunger induced by small and large duodenal loads of isotonic glucose
Authors: Rezek M , Havlicek V , Novin D
Published: December 2017

Hepatic-portal infusions of small or large flucose loads in the rabbit had little or no stimulating effect on postinfusion food intake. However, marked differential changes in appetite were observed when small and large glucose loads were infused into the duodenum. The satiating effect of small glucose loads contrasted sharply with an unusually high increase in food intake triggered by the infusions of larger amounts of glucose into the duodenum. The results are interpreted in terms of a possible involvement of the enteroinsular mechanism in the regulation of food intake. This mechanism is bypassed and its influence on food intake eliminated when glucose is infused directly into the portal circulation. The positive relationship between large amounts of alimentary carbohydrates and overeating is seen as a factor that may actively promote the development of obesity and diabetes mellitus.
Dispersed rat parotid acinar cells. III. Characterization of cholinergic receptors
Authors: Mangos JA , McSherry NR , Barber T
Published: December 2017

The in vitro characterization of cholinergic receptors in dispersed rat parotid acinar cells was accomplished through investigations of the net transmembrane fluxes of K in response to exposure of the cells to selected cholinergic agonists and antagonists. Interaction of acetylcholine bromide (ACh) and carbamylcholine (carbachol) with the cholinergic receptors resulted in rapid net efflux of K from the cells. This cellular response was demonstrable in concentrations of carbachol as low as 10(-8) M. With gradual increase in the concentrations of the agonist an increase in the K efflux was observed up to 10(-5) M. At higher concentrations of this cholinergic agonist no further increases in the net K efflux were observed. The response of the cells to cholinergic agonists was inhibited by atropine but not by the adrenergic antagonists phentolamine or propranolol, suggesting cholinergic agonist-antagonist interactions at the receptor site. The dispersed rat parotid acinar cells appear to have functionally intact cholinergic receptors and could be used as valuable experimental tools for the study of receptor physiology and pharmacology as well as of other aspects of secretory function at the cellular level.
Recirculation and reutilization of micellar bile lecithin
Authors: Robins SJ
Published: December 2017

Bile lecithins, solubilized in micellar bile salt and radiolabeled in the 1-acyl fatty acid, phosphorus, and choline positions, were infused in the small bowel of fasted rats. Absorption of each label was virtually complete after 24 h. However, these lecithins were extensively hydrolyzed in the bowel lumen as well as after absorption, and neither the fatty acid nor phosphorus was significantly retained in the enterohepatic circulation or reutilized for biliary lecithin synthesis. In contrast, while choline was also dissociated from absorbed lecithin, choline was instead retained in the liver, reincorporated into newly synthesized hepatic lecithin, and sercreted in biliary lecithin in 10-fold greater amounts than either the fatty acid or phosphorus. However, the extent of choline incorporation into bile lecithin was limited and was not further increased when free choline was directly injected into the portal vein. The data therefore suggest that although only choline of absorbed lecithin is retained in the enterohepatic circulation and preserved for new biliary lecithin synthesis, exogenous choline utilization is regulated by the size of the available hepatic pool.
Properties of canine tissue thromboplastins from brain, lung, arteries, and veins
Authors: Gonmori H , Takeda Y
Published: December 2017

Properties of the protein moieties of canine tissue thromboplastins (TTP's) from brain (BTTP), lung (LTTP), arteries (ATTP), AND VEINS (VTTP) were determined. The maximum specific activity of each protein moiety after its relipidation was obtained when the phospholipid-delipidated TTP ratio was 0.32 and was 1,395 U/mg BTTP, 1,130 U/mg LTTP, 630 U/mg VTTP, and 435 U/mg ATTP. The amino acid contents of the protein moieties of LTTP, ATTP, and VTTP were closely similar, but that of BTTP was significantly different. The Ouchterlony analysis showed that BTTP did not react at all with the antibody against VTTP, but that three other TTP's did and showed the reaction of complete identity. Then, the reactivity of 125-I-labeled TTP's with the anti-VTTP antibody was studied. The results showed that 0.79 +/- 0.01 (SD) % of [125I]BTTP, 10.24 +/- 0.5 (SD) % of [125I]LTTP, 19.4 +/- 0.2 (SD) % of [125I]VTTP, and 5.88 +/- 0.4 (SD) % of [125I]ATTP added were bound to the antibody in 2 h. Next, the molecular weight of each was determined by Sephadex G-200 filtration, which averaged 80,000 +/- 4,000 (SD) ([125I]BTTP), 113,000 +/- 5,000 (SD) ([125I]LTTP), 62,000 +/- 3,000 (SD) ([125I]ATTP), and 47,000 +/- 2,000 (SD) ([125I]VTTP). Finally, the plasma behavior of each was studied in four dogs. The plasma half-life averaged 8.1 +/- 0.24 (SD) h ([125I]BTTP), 14.6 +/- 0.5 (SD) h ([125I]LTTP), 7.38 +/- 0.48 (SD) h ([1252]ATTP), and 24.3 +/- 0.9 (SD) h ([125I]VTTP). These results indicate that the protein moieties of canine TTP's from brain, lung, arteries, and veins are closely similar in some aspects but dissimilar in others and are definitely not identical.
Neuropharmacological characterization of insulin-sensitive CNS glucoregulator
Authors: Szabo O , Szabo AJ
Published: December 2017

Regional insulinization of the central nervous system (CNS) through the carotid artery causes an immediate decrease of the systemic blood sugar level in rats under light barbiturate anesthesia. Cervical vagotomy or intraperitoneal or intravenous atropine pretreatment results in partial inhibition of the systemic hypoglycemic response that follows intracarotid insulin injection. Intraperitoneal, intravenous, or intracarotid pretreatment with phentolamine or propranolol or intracarotid pretreatment with epinephrine had no effect on this centrally induced hypoglycemia. Intracarotid atropine injection immediately prior to intracarotid insulin injection completely abolished the systemic hypoglycemic response. Pretreatment with neostigmine administered intravenously prevented the inhibitory effect of intracarotid atropine on the hypoglycemic response that followed intracarotid insulin injection. It is consluded that the insulin-sensitive glucoregulator center of the CNS is under cholinergic influence, or its efferent pathways have a centrally located cholinergic synapsis.
Aortic nerve-activated cardioinhibitory neurons and interneurons
Authors: Schwaber J , Schneiderman N
Published: December 2017

Unit activity evoked by electrical stimulation of the aortic and vagus nerves was recorded in the dorsal motor nucleus and nucleus solitarius of unanesthetized rabbits. Cardioinhibitory cells which showed antidromic activation to stimulation of the vagus nerve and synaptic activation to stimulation of the aortic nerve were localized in lateral dorsal motor nucleus 0.5-0.8 mm anterior of the obex. Additionally, units were found that appeared to be interneurons in the medullary pathway subserving baroreceptor reflex effects on cardioinhibitory neurons. These cells were activated by aortic, and usually vagus, nerve stimulation, appeared to be polysynaptically activated, and were located in medial nucleus solitarius rostral to the obex. Neurons reflecting a cardiac rhythm but not activated by aortic nerve stimulation were also observed.
Thiocyanate inhibition of ATPase and its relationship to anion transport
Authors: Solomon RJ , Silva P , Bend  , Epstein FH
Published: December 2017

Adenosine triphosphatase activity not dependent on sodium or potassium but inhibited by thiocyanate is present in broken-cell homogenates of eel gill and rat kidney. This enzymatic property is predominantly associated with mitochondria, although thiocyanate-inhibited ATPase can also be detected in microsomes with little or no mitochondrial contamination as measured by the activity of the mitochondrial marker enzyme succinic dehydrogenase. When eels are transferred from fresh to salf water, thus increasing active outward transport of chloride across the gill, the thiocyanate-inhibited ATPase of gill microsomes does not change, though the activities of succinic dehydrogenase and Na-K-ATPase in gill homogenates are augmented. The thiocyanate-inhibited ATPase of homogenates of outer renal medulla does not differ from that of renal cortex, in contrast to Na-k-atpase which is higher in renal medulla than in cortex. The data do not support a role for thiocyanate-inhibited ATPase in active chloride transport by epithelial tissues.
Prostaglandin control of renal circulation in the unanesthetized dog and baboon
Authors: Swain JA , Heyndrickx GR , Boettcher DH , Vatner SF
Published: December 2017

Effects of indomethacin and meclofenamate, inhibitors of prostaglandin synthesis, were evaluated in the regulation of renal blood flow in conscious and anesthetized dogs and in tranquilized baboons, instrumented with arterial pressure catheters and renal blood flow probes. Indomethacin, 10 mg/kg, did not alter renal blood flow or resistance significantly in the conscious dog. In the anesthetized dog, however, indomethacin caused a reduction in renal blood flow (25 +/- 3% of control) and an elevation of renal vascular resistance (45 +/- 8% of control). Meclofenamate, 4 mg/kg, reduced renal flow (12 +/- 2%) and increased renal vascular resistance 15 +/- 4% in conscious dogs. In conscious dogs and tranquilized primates, indomethacin and meclofenamate reduced the reactive hyperemia in the renal bed after 15 s occlusion from a control of 36 +/- 5 ml to 6 +/- 2 ml, and after 45 s occlusion from a control of 98 +/- 9 ml to 17 +/- 5 ml. Methoxamine (10-50 mug/kg per min) and angiotensin II (0.03-0.12 mug/kg per min), infused in graded doses, induced significantly greater renal vasoconstriction in conscious dogs in the presence of indomethacin. Thus, in the conscious animal, prostaglandins appear to play only a minor role in the control of the renal circulation at rest, but are of greater importance in mediating the renal responses to reactive hyperemia and to vasoconstriction.
Na+ dependence of in vitro pancreatic amylase release
Authors: Williams JA
Published: December 2017

The effects of Na+ on the in vitro release of amylase from mouse pancreas were studied. Replacement of Na+ in the medium by Tris, choline, or sucrose blocked the stimulation of amylase release by bethanechol and caerulein, whereas replacement by Li+ was without effect. The inhibiton was rapid and reversible, with stimulated amylase release linearly related to the log of the medium Na+ concentration over the range of 20-100 mM Na+. In contrast to the inhibition of amylase release stimulated by physiological secretagogues, enzyme release stimulated by the Ca2+ ionophore A23187 was unaffected by removal of Na+ from the medium. Tissue and intracellular Na+ and K+ contents were unchanged after stimulation of secretion by physiological stimulants. It is concluded that Na+ may be important in the early steps of stimulus-secretion coupling leading to the putative rise in intracellular Ca2+ that triggers pancreatic enzyme release.
Oxygen transport of colloidal fluorocarbon suspensions in asanguineous rabbits
Authors: Gollan F , Aono M , Flores A
Published: December 2017

In anesthetized, oxygen-breathing rabbits, the entire blood volume was exchanged with a 20% colloidal fluorocarbon fluid suspension of high gas solubility. In contrast to the control animals with acute isovolemic and hypervolemic hemodilution, the fluorocarbon suspension prevented the decrease in arterial oxygen content below a hematocrit of 13%. However, the more pronounced effect of the fluorocarbon suspension on oxygen delivery occurred at higher hematocrits and was due to its efficiency as a plasma expander, since it increased the cardiac output even above the level of the hypervolemic hemodilution group. The fluorocarbon suspension also raised arterial blood pressure and total peripheral resistance due to its increased viscosity. Thus, in mild hemodilution, the fluorocarbon suspension kept oxygen utilization in the normal range by increasing cardiac output, and in extreme hemodilution it improved oxygen utilization by also raising the arterial oxygen content and arterial blood pressure. The survival time of the isovolemic control animals was 31.6 min, it was extended to 57.8 min in the hypervolemic control animals, and the rabbits with the fluorocarbon suspension lived for 124.8 min.
Secretion of K and fluid by rat submaxillary during sympathetic nerve stimulation
Authors: Schneyer LH
Published: December 2017

Stimulation of the sympathetic innervation to rat submaxillary gland is known to evoke saliva which contains high concentrations of potassium (130-160 meq/liter). Relationships were examined between salivary [K] and several parameters of the stimulation, including pulse frequency and duration of the stimulus train and rate of flow of the evoked saliva. Secretion of sympathetically evoked saliva was found to occur in two phases. After stimulation was started, flow rate was relatively high initially, and then decreased to a lower, relatively steady value. Initial and steady flow rates were maximal when stimulus frequency was 10 Hz. Salivary [K] was lowest initially, and, at that time, was inversely related to flow rate. At steady flow, [K] was flow independent. While salivary [K] was lower during initial than during steady secretion, the rate of K secretion was initially higher. During the initial phase, K decreased in the gland, and this decrease was sufficient to account for the increased amount of K secreted in initial saliva and for the increased initial flow.
Reduced beta-adrenergic responsiveness in hypothyroid rats
Authors: Fregly MJ , Nelson EL  , Resch GE , Field FP , Lutherer LO
Published: December 2017

The beta-adrenergic agonist isoproterenol (100-200 mug/kg body wt sc) induces vasodilation and an increase in skin temperature of the tail of the euthyroid but not the hypothyroid rat. Administration of thyroxine (25 mug/kg body wt per day) to rats made hypothyroid by means of the antithyroid drug aminotriazole (0.5 g/kg of foof) returned responsiveness to control level. Reduced responsiveness to isoproterenol occurred between 1 and 5 wk of treatment with aminotriazole. Increase in tail skin temperature induced in euthyroid rats by isoproterenol was blocked by administration of propranolol (7.5 mg/kg ip). Other beta-adrenergic-induced responses, including increased water intake and increased plasma glucose concentration, also were reduced in hypothyroid rats and returned to control level by administration of thyroxine. Thus, hypothyroidism appears to be accompanied by a reduced beta-adrenergic responsiveness as assessed by changes in tail skin temperature, water intake, and plasma glucose concentration after injection of isoproterenol. Since administration of thyroxine returned the responses of hypothyroid rats to control levels, it appears that thyroxine is important in maintaining beta-adrenergic responsiveness under these conditions.
Distributions of spike bursts in cat duodenum
Authors: Sancholuz AG , Croley TE  , Glover  , Macagno EO , Christensen J
Published: December 2017

The histograms of spike bursts over short distances were examined in the isolated cat duodenum with multiple electrodes arranged circumferentially and longitudinally. At a single cross section of the duodenum, spike bursts occurred simultaneously in any single slow-wave cycle, but all eight monitored sites in the circumference participated simulatenously only in a bout 25% of the spike-burst cycles. There also were wide variations in the incidence of spike bursts at different locations in a planar cross section. In a longitudinal section, net level of activity over short distances varied widely. Also, spike bursts were out of phase in the longitudinal axis, appearing to spread caudad; 80% of spike burst groups involved less than an average of 5.5 consecutive electrode sites (spaced at 5-mm intervals). Since spike bursts seem to be correlated with ring contractions of the circular muscle, the fact that they appear sequentially in time along the duodenum indicates that such contractions must always be peristaltic. An estimated 80% of such contractions sweep less than about 3 cm. Records of spike bursts from a single electrode do not accurately reflect activity beyond that one point site.
Induction processes in blood-brain transfer of ketone bodies during starvation
Authors: Gjedde A , Crone C
Published: December 2017

Fed and starved rats were studied on successive days during a 5-day starvation period. The ability of ketone bodies to pass the blood-brain barrier was estimated by single common carotid injections of labeled ketone bodies and water, and results were expressed as the ratio between the normalized activities of tracers in tissue and blood, the brain uptake index (BUI). BUI of D-3-hydroxybutyrate and acetoacetate decreased as their total concentrations increased in the injectate bolus: BUI of D-3-hydroxybutyrate decreased significantly from 8% at 0.2 mM to 3--4% at 20.2 mM in fed rats and from 11.5% at 0.2 mM to 6% at 20.2 mM in starved rats, indicating saturation of the uptake mechanism. The BUI of both ketone bodies increased significantly with increasing duration of starvation, indicating adaptation to ketonemia. Enzymatic kinetics explained the uptake behavior of D-3-hydroxybutyrate in both fed and starved rats and involved a rise of Km and Vmax during starvation consistent with a doubling of the transport rate at the degree of ketonemia found in starved rats. The uptake of glucose was not influenced by starvation or ketonemia.