bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of the components of bile flow in the rhesus monkey
Authors: Strasberg SM , Ilson RG , Siminovitch KA , Brenner D , Palaheimo JE
Published: December 2017

Bile flow studies were performed in three groups of awake rhesus monkeys. In the first group, the increase in bile flow stimulated by secretin was not accompanied by an increase in erythritol-14C clearance. Resection of the gastric antrum and small intestine in the second group resulted in stable bile flow at fixed bile salt secretion rates. Linear regression lines for bile flow versus bile salt secretion rate and erythritol-14C clearance versus bile salt secretion rate were parallel, and the Y-axis intercept for the latter was consistently higher than for the former. We concluded that erythritol-14C clearance equals canalicular flow, and ductular reabsorption is constant at all bile salt secretion rates in this species. Bile flow was studied during fasting and feeding, over 6 days, in the third group. A model incorporating four bile flow components was developed and tested by multivariate regression analysis. The data fit the model quite well, explaining greater than 90% of the variation in bile flow. A method of measuring the contribution to bile flow of each of the four components is provided.
Impaired renal response to parathyroid hormone in potassium depletion
Authors: Beck N , Davis BB
Published: December 2017

In potassium depletion, a possible alteration of the proximal tubular response to parathyroid hormone (PTH) was evaluated in rat kidney. 1) There were impairments of both phosphaturic and urinary cyclic AMP responses to PTH. The site of the impairment was further investigated by studying the PTH-dependent cycle AMP system in renal cortex. 2) There was a lesser increase of cyclic AMP concentration by PTH in potassium-depleted slices, indicating the lesser urinary cyclic AMP was due to the specific impairment of PTH-dependent cyclic AMP in the kidney. 3). The activation of adenylate cyclase by PTH was impaired , but phosphodiesterase activity was not affected by potassium depletion, indicating the impairment of cyclic AMP generation was due to inhibition of adenylate cyclase. 4) The phosphaturic response to dibutyryl cyclic AMP infusion was also significantly less in the potassium-depleted animals, indicating the step subsquent to the cyclic AMP generation is also impaired. All above results indicate that, in potassium depletion, the renal response to PTH is impaired, and the impairment is both within the step of cyclic AMP generation and after the cyclic AMP generation.
Influence of crossbridge compliance on the force-velocity relation of muscle
Authors: Grood ES , Mates RE
Published: December 2017

It is shown that muscle models which describe force generation as being dependent on the extension of the individual crossbridges produce a force-velocity relation of the form: Vf= Visotonic--1/KHS dP/dt. The derivation of this equation is independent of the details of activation and the kinetics of the crossbridges. The velocity, Vf, represents the relative filament velocity, and Visontonic is the relative filament velocity which would maintain a constant muscle force. P. The quantity KHS is the net stiffness of all the force-generating crossbridges in one-half a sarcomere. Experimental methods for determining KHS are suggested . To study the force-velocity relation, computer simulations based on A. F.Huxley's 1957 kinetic model were conducted for isometric and isotonic twitch contractions. The relative filament velocity is found to depend on the contraction mode, exhibiting a sudden increase in an isometric-to-isontonic changeover and a decrease in the reverse process.
Mechanisms of acid disposal in canine duodenum
Authors: Dorricott NJ , Fiddian-Green RG , Silen W
Published: December 2017

Distal duodenal pouches chronically excluded from the intestinal stream were perfused in seven awake dogs by a constant-circulation technique using isomolar solutions containing 60-120 mM HCl. The rate of disappearance of hydrogen ions (H+) and net ion movements was measured. In all experiments there was a loss of H+ from the perfusate accompanied by a gain of sodium (Na+), potassium (K+) and chloride (Cl-), together with an increase in volume and a decrease in osmolality. The magnitude of this H+ loss was a function of instillate [H+]. The H+ lost by neutralization was separated from that lost by diffusion by calculations based on the assumption that the observed changes in somolality were the result of neutralization by bicarbonate (HCO3-). The bulk of the acid (67%) was lost by neutralization, the remainder back-diffusing in a one-to-one exchange for diffusable Na+. This ability to dispose of acid decreased with increasing age of the pouches due to a diminished volume of HCO3- secretion, the magnitude lost by backdiffusion remaining unchanged.
Uptake of adenosine by dispersed chich embryonic cardiac cells
Authors: Mustafa SJ , Rubio R , Berne RM
Published: December 2017

Adenosine is involved in the regulation of coronary blood flow, but its mechanism of action is not clear. The present investigation is an attempt to understand the mechanism(s) of uptake of adenosine in dispersed chick embryonic cardiac cells and its relationship to the adenosine hypothesis. Adenosine is readily taken up by these cardiac cells, and a small fraction is incorporated into adenine nucleotides, whereas a major fraction is deaminated to inosine. The mechanism of uptake is different in 12- to 15-day-old chick embryos compared to 16- to 22-day-old embryos. The younger embryo heart cells show the incorporation of adenosine into adenine mononucleotides of the incubation medium as well as all the adenine nucleotides of the cells, whereas the older embryo heart cells show incorporation of adenosine only into the adenine nucleotides of the cells. The isolated cells used in the present study do not leak any significant amounts of adenosine kinase and/or nucleotides, and free adenosine was not found in the cells, even with extracellular concentrations as high as 1 mM. The absence of free adenosine in isolated dispersed cells reflects the activities of adenosine kinase and adenosine deaminase and is compatible with the adenosine hypothesis for the regulation of coronary blood flow.
Effect of glucose on lipolysis and on release of lipolytic products in isolated adipocytes
Authors: Naito C , Okada K
Published: December 2017

Isolated adipocytes were prepared from epididymal adipose tissues removed from rats which had been fed or starved for 48 h (fed adipocytes or fasted adipocytes). These cells were incubated at 37 degrees C for 90 min in media containing 0, 3, or 30 mM glucose, with or without norepinephrine (1.0 mug/ml). Then the concentrations of free fatty acids (FFA) and free glycerol (FG) in the total mixture (medium plus cells) and in the medium alone were measured. Addition of glucose to the medium increased the total PG, presumably by increasing the basal lipolysis, and it decreased the intracellular retention ratio of FG (the ratio of intracellular FG to total FG). Addition of glucose did not change the total FFA, but decreased the FFA/FG ratio, presumably by increasing reesterification. The increase in FG and decrease in the FFA/FG ratio on addition of glucose were greater in fed than in fasted adipocytes. The intracellular retention ratio of FFA also decreased on addition of glucose. Glucose enhanced norepinephrine-induced lipolysis (release of free glycerol), and this effect of glucose was greater in fasted adipocytes. However, the increase in FFA in fasted adipocytes induced by norepinephrine was not altered by addition of glucose. In fed adipocytes norepinephrine decreased the total FFA in the presence of glucose. Reesterification of FFA following norepinephrine was increased by addition of glucose. Norepinephrine decreased the intracellular retention ratios of FG and FFA in the presence of glucose. These results suggest that the passage of the lipolytic products, FFA and FG, through the cell membranes may not occur by simple diffusion, but may require energy.
Development of autonomic control of fetal circulation
Authors: Nuwayhid B , Brinkman CR  , Su C , Bevan JA , Assali NS
Published: December 2017

Development of parasympathetic and sympathetic reflexes controlling heart rate, vascular pressures, and blood flows was investigated in fetal lambs weighing 300-5,800 g (65-165 days' gestation). Cardiovascular responses to veratridine injections, atrial stretching, bilateral cervical vagotomy, and cholinergic blockade with atropine were used to test parasympathetic activities. Responses to propranolol and phenoxybenzamine were used to test beta- and alpha-adrenergic activities. Autonomic ganglionic blockade and stimulation provided additional information on both cholinergic and adrenergic systems. Fetal responses to various tests were compared to those of the mother. Results show: a) little parasympathetic tone on resting heart rate and other circulatory functions exists prior to fetal maturity; b) despite the feeble resting tone, the parasympathetic system is capable of exerting significant control when stimulated in both premature and mature fetuses, the capability increases as fetus approaches term; c) alpha- and beta-adrenergic tone in control of resting heart rate and peripheral circulation exists in early fetal life and increases as the fetus reaches maturity, and both adrenergic receptors respond strongly to stimuli in immature, premature, and mature fetuses; d) in immature fetuses, veratridine does not elicit a vagally mediated reflex; instead, it produces a centrally mediated alpha- and beta-adrenergic stimulation; e) the fetal cardiovascular response to any given test is dampened by the existence of the various vascular shunts, the umbilicoplacental circulation and, possibly, by incomplete maturation of vasomotor tone.
Localization of rapidly exchangeable calcium in mammalian heart muscle
Authors: Kolbeck RC , Paradise NF , Visscher MB
Published: December 2017

Two new methods were used to calculate net labeled Ca++ compartmental influx into rabbit myocardium: 1) continuous measurements of arteriovenous differences in 45Ca levels are corrected for longitudinal mixing and for varying transit times by a double-isotope technique with the relatively impermeant 131I-labeled albumin as the referent substance; 21 tritiated sucrose and 45Ca contents were measured in ventricular muscle after perfusion with the doubly labeled perfusate and washout of aqueous perfusate with fluorocarbon 80. Both methods yielded similar results. Only 52% of the Ca++ efflux from the vascular bed during the rapid flux period can be accounted for as Ca++ in interstitial water under control perfusion conditions. Contracture induced by substituting K+ for Na+ in the perfusate brings the fraction not accounted for as Ca++ in interstitial water from 48 to 60% of the total in 5 min. When irreversible contracture is induced by return to normal [Ca++] after short periods of excitation-contraction uncoupling due to zero [Ca++] perfusion, the fraction not accounted for as Ca++ in interstitial water is 68% in 5 min.
Sites of organic acid production and absorption in gastrointestinal tract of the pig
Authors: Argenzio RA , Southworth M
Published: December 2017

The relationship between diet, pH, and microbial digestion of carbohydrate was examined in 24 pigs fed either a conventional or a low-protein, high-cellulose experimental diet and sacrificed 2, 4, 8, or 12 h after a meal. In animals fed the control diet contents of the cranial half of the stomach demonstrated marked, cyclic fluctuations in pH and high concentrations of organic acids. Contents of the caudal (glandular) half were lower in both pH and organic acid concentration. Despite concentrations of volatile fatty acids (VFAs) as high as 250 meq/liter in the large intestine, the pH remained relatively neutral. The VFA levels remained relatively constant throughout the length of the colon. The VFA transport across isolated gastric and large intestinal mucosa also was examined. All four types of gastric mucosa absorbed and transported VFA at substantial rates. Mucosa of pig cecum and colon transported VFA at much greater rates than gastric mucosa and greater rates than previously determined in equine large intestinal mucosa or even bovine rumen epithelium. Comparison with results of earlier studies in the pony suggested that the higher concentration of VFA in the large intestinal contents of pigs was due to the more rapid rate of digesta passage rather than to less efficient absorption of fatty acids.
Placental diffusing capacity in unanesthetized rabbits
Authors: Rocco E , Bennett TR , Power GG
Published: December 2017

The purpose of this study was to determine the placental diffusing capacity of CO in unanesthetized rabbits. A standard dose of CO was administered to 18 near-term rabbits, and at time intervals varying from 5 min to 4 h maternal and fetal blood samples were analyzed for carboxyhemoglobin saturation (HbCO). Following administration of CO, the maternal HbCO rose rapidly within the 1st min and remained nearly constant for the remainder of the experiment. The fetal HbCO after CO introduction to the mother rose as CO crossed the placenta from maternal to fetal blood. After 15 min the fetal HbCO rose to equal the maternal HbCO averaging 18.5%. The fetal HbCO after 1 h averaged 33% saturation, 1.7-fold greater than the maternal HbCO at 1 h. Thereafter there was little further fetal rise and apparently equilibrium was reached. The average placental diffusing capacity for CO was 2.3 ml/(min times mmHg times kg), a value fourfold higher than has previously been reported in anesthetized sheep and dogs. Possible reasons are species difference, effects of posture, influence of anesthesia and surgery, and effects of an open versus intact uterus.
Dimensional analysis of the left ventricle: effects of acute aortic regurgitation
Authors: Leshin SJ , Horwitz LD , Mitchell JH
Published: December 2017

The effects of acute severe aortic regurgitation on the left ventricle were investigated in conscious, chronically instrumented dogs. Left ventricular dimensions and volumes were measured from biplane cineradiographs of beads positioned near the endocardium. Data were collected before and after the production of aortic regurgitation by a catheter technique. The aortic regurgitation resulted in increases in mean aortic pulse pressure from 44 to 73 mmHg (P smaller than 0.001), heart rate from 87 to 122 beats/min (P smaller than 0.02), and left ventricular end-diastolic pressure from 11 to 25 mmHg (P smaller than 0.05). Mean end-diastolic volume rose from 61 to 69 cc (P smaller than 0.001), while end-systolic volume remained unchanged at 37 cc. The end-diastolic dilatation following regurgitation was asymmetrical in that the increase in size was due principally to an increase in the septal-lateral axis. The acute volume load of aortic regurgitation was accomplished by an increase in end-diastolic volume, i.e., the Frank-Starling mechanism. The tachycardia probably reflects augmented cardiac sympathetic activity, but the constant end-systolic volume at a similar mean systolic pressure suggests that the net contractile state was unchanged.
Effect of hypothalamic lesions on immediate hypersensitivity
Authors: Schiavi RC , Macris NT , Camerino MS , Stein M
Published: December 2017

Bilateral electrolytic lesions were placed in the anterior basal hypothalamus of male Hartley-strain guinea pigs. The animals with anterior hypothalamic lesions and a group of sham-operated controls were sensitized 5-10 days postoperatively with ovalbumin in modified Freund's adjuvant. At 18-22 days following sensitization both groups were randomly divided into three subgroups and challenged by intrajugular injections of three different antigen doses. Anaphylactic death and the severity of anaphylaxis in the survivors were recorded. Antibody titers were determined prior to challenge with use of the passive cutaneous anaphylaxis technique. Serial sections of each brain were made for lesion localization. Significant protection against anaphylaxis was found in guina pigs with symmetrical lesions in the anterior hypothalamus. No significant differences in antibody titers were observed between the lesion and sham-operated groups. There were no significant differences in the response of isolated muscle strips from anterior-lesioned and sham-operated guinea pigs to exogenous histamine. Anterior hypothalamic lesions of size and location comparable to those that provided protection against lethal anaphylaxis did not modify the anaphylactic response of isolated ileum from actively sensitized animals or following passive sensitization in vitro.
Effects of catecholamines on myocardial endogenous substrates and contractility
Authors: Crass MF  , Shipp JC , Pieper GM
Published: December 2017

The effects of epinephrine and norepinephrine on triglyceride and glycogen metabolism and contractility were studied in isolated perfused working rat hearts. Hearts with lipids prelabeled in vivo with [1-14C]palmitate were perfused with bicarbonate buffer containing 5.5 mM glucose, with or without 0.6 mM palmitate (3% albumin), and varying concentrations of catecholamines. Direct evidence for catecholamine-stimulated myocardial triglyceride lipolysis was obtained and, for the first time, was shown to be concentration-dependent. Also, catecholamines enhanced heart triglyceride fatty acid oxidation in concentration-dependent fashion. Stimulation of lipolysis and oxidation was observed only in hearts perfused with buffer containing glucose as the sole substrate, and was inhibited in the presence of 0.6 mM palmitate. Palmitate inhibited net glycogenolysis in the absence of catecholamines, but had little effect on epinephrine-stimulated glycogenolysis. Therefore, with free fatty acids present, mobilization of endogenous triglycerides to meet the increased metabolic demands of catecholamine stimulation is minimized; this is due, possibly, to enhanced utilization of exogenous free fatty acids and to inhibition of net lipolysis.
Effect of tetraethylammonium on tonic airway smooth muscle: initiation of phasic electrical activity
Authors: Kroeger EA , Stephens NL
Published: December 2017

We have previously shown that in the presence of tetraethylammonium (TEA, 6.7-67 mM) phasic mechanical activity and a myogenic response (MR) to quick stretch are produced in normally multi-unit tracheal smooth muscle. The present studies were designed to investigate the electrophysiological basis for these changes in the mechanical properties of the muscle. Intracellular recordings showed that in the presence of TEA the membrane was partially depolarized and trains of small (8-20 mV), decrementally conducted action potentials were produced spontaneously at a frequency of 15-20/min. Action potentials could also be stimulated by external electrodes, and the conduction velocity over short distances was 0.84 plus or minus 0.2 cm/s. Membrane conductance and rectification, as measured by the magnitude of electrotonic potentials in response to external stimulation, were reduced in the presence of TEA. The length constant was increased from 1.6 plus or minus 0.1 to 2.8 plus or minus 0.2 mm. These results are consistent with the notion that TEA produces phasic membrane electrical activity by reducing P-K.
Effects of bile salts on amphibian gastric mucosa
Authors: Silen W , Forte JG
Published: December 2017

The effect of five different bile salts on the mucosal or serosal surface of isolated bullfrog gastric mucosa was investigated. Serosal exposure (30 min) to 15-40 mM taurocholate (TCA) or taurodeoxycholate (TDCA), 10-40 mM deoxycholate (DCA), or 2.5-7.5 mM cholate (CA) typically produced a marked increase in resistance (R) and a decrease in potential difference (PD), short-circuit current (I-sc), and H+ secretion. Flux of 36Cl from serosal to mucosal solution decreased progressively. The flux of [14C]sucrose across the mucosa was slightly decreased. Microscopy showed condensation of the parietal cells. Mucosal exposure (30 min) at concentrations above 2.5 mM DCA or CA and 15 mM TCA and TDCA caused a marked decrease in R, PD, I-sc, and H+ secretion, and the flux of [14C]sucrose across the mucosa was increased. Extreme destruction of the surface mucous cells was the primary histologic finding. The effect of dehydrocholate was identical to that of TCA. Mucosal bile salts cause an increased permeability primarily by injury of the surface epithelium whereas serosal bile salts affected primarily the oxyntic cells.
Acyl-CoA inhibition of adenine nucleotide translocation in ischemic myocardium
Authors: Shug AL , Shrago E , Bittar N , Folts JD , Koke
Published: December 2017

The translocation of adenine nucleotides across the inner mitochondrial membrane and the tissue concentration of long-chain acyl-CoA esters were studied in dog heart after experimental myocardial ischemia. Ligation of the anterior coronary artery initiated events leading to an early decrease in adenine nucleotide translocase activity. A reciprocal increase in the concentration of heart tissue long-chain acyl-CoA esters was also observed. Adjacent nonischemic tissue showed changes intermediate between that of ischemic and normal heart tissue. It is postulated that a decrease in fatty acid oxidation after myocardial ischemia would lead to an accumulation of long-chain acyl-CoA esters, which in turn would inhibit adenine nucleotide translocation. The net result would be a lowering of the energy charge of the cell, adversely affecting muscle contraction and electrical conduction.
Alpha-M-fetoprotein in serum of rats after experimental manipulation in the oral cavity
Authors: Rosenmann E , Sela J , Okon E , Dishon T , Boss JH
Published: December 2017

Alpha-M-fetoprotein (AMFP) was detected in the serum of rats subjected to intraoral manipulations, i.e., instillations into the parotid gland and injections into the gingival mucosa of saline or foreign proteins. The identity of AMFP with acute-phase protein is pointed out.
Cold resistance of the brain during hibernation. III. Evidence of a lipid adaptation
Authors: Goldman SS
Published: December 2017

The composition of membrane-bound lipids of brain from both warm-adapted and hibernating hamsters were different in the complex lipid fraction as well as their fatty acyl chains. During hibernation the content of cholesterol was less, but there were greater amounts of both the phosphatidylcholines and phosphatidylethanolamines. There were small but significant increases in monounsaturated fatty acids as well as arachidonic acid in all the glycerophosphatides of the hibernating hamster, whereas a decrease in isomyristic acid was o0served in the sphingomyelins. The most significant changes observed occurred in the fatty aldehyde composition of ethanolamine plasmalogen. A dramatic increase in oleyaldehyde was observed during hibernation. These changes in membrane-bound lipids may account for the cold-resistant properties of the brain during hibernation by retaining the fluid nature of the cell membrane.
Hydrocortisone restoration of the pH-dependent metabolic responses to catecholamines
Authors: Uajima M , Ui M
Published: December 2017

Feeding NH4CL to fasted rats caused changes of blood levels of lactate, glycerol, and insulin, hepatic levels of glycogen and phosphorylase, and muscle levels of glycogen and glucose 6-P in the direction opposite to the changes induced by respiratory alkalosis. The effects of epinephrine and isoproterenol in vivo on these metabolic indices, which are classified as their function mediated via the adrenegic beta receptor, were potentiated by NH4CL feeding in contrast to their attenuation in alkalosis. The prior treatment of the rat with hydrocortisone was very effective in overcoming the alkalosis-induced inhibition of the beta-receptor-mediated metabolic actions of epinephrine and isoproterenol, such as the activation of liver phosphorylase, accumulation of muscle hexose phosphates, and stimulation of pancreatic secretion of insulin. Epinephrine sensitivity of the liver and muscle levels of cyclic AMP was not altered by the hydrocortisone therapy or inductions of alkalosis and acidosis. The mechanism for the hydrocortisone restoration of the adrenergic beta functions in alkalosis is discussed as related to its permissive effect.
Ion transport across the excised bullfrog lung
Authors: Gatzy JT
Published: December 2017

Fluxes of ions and water across the short-circuited, excised bullfrog lung were determined by radioisotope techniques. The unidirectional flows of Na+, K+, Ca++, TcO4 minus, HCO3 minus, gluconate, rho-aminohippurate, dinitrophenolate, SO4 equal to, and water were symmetrical. Both HCO3 minus fluxes were reduced by acetazolamide. In contrast, Cl minus, Br minus I minus, and SCN minus movement from serosa to mucosa exceeded the flux in the opposite direction. Net Cl minus transport followed the kinetics of a saturable process and was inhibited by dinitrophenol and hypoxia. These results indicate an active secretion of halide anions and SCN minus into the lumen. Attempts to demonstrate Br minus anatagonism of Cl minus transport were equivocal. Cl minus transport accounted for 50 percent minus of the early short-circuit current but after 90 min the two measurements were equal. Incubation of the lung in bicarbonate-free Ringer revealed unequal decreases in the H+ concentration of the bathing solutions. Net "base" addition to the serosal solution was reduced by prior removal of the blood from the pulmonary vasculature. Therefore, "base" release could not be localized to the epithelia. The Na+, K+, Ca++ and Cl minus composition of the lung tissue was unchanged over 3 h. Since tissue and, hence cell Cl minus is lower than the concentration in the bathing solution the Cl pump is probably located in the luminal border of the alveolar epithelial cell.
Effect of extragastric and truncal vagotomy on pancreatic secretion in the dog
Authors: Debas HT , Konturek SJ , Grossman MI
Published: December 2017

In four dogs with chronic pancreatic and gastric fistulas, dose-response studies of pancreatic bicarbonate and protein secretion were done with intravenous infusions of secretin, octapeptide of cholecystokinin (OP-CCK), and 2-deoxyglucose (2-DG). The pancreatic response to a meal and to duodenal perfusion of graded concentrations of HCl, sodium oleate, and tryptophan were also studied. These observations were repeated after division of both the hepatic and celiac vagal branches to produce extragastric vagotomy, and subsequently after transthoracic truncal vagotomy. The responses to secretin, OP-CCK, and to duodenal perfusion of HCl were either unaltered or only slightly decreased by either extragastric or truncal vagotomy. Basal pancreatic secretion and the responses to duodenal perfusion of oleate and tryptophan were markedly depressed by extragastric vagotomy. These findings indicate that tonic vagal activity contributes to basal pancreatic secretion but has little effect on the response of the pancreas to secretin or CCK or on the release of secretin from the intestine. The decreased pancreatic response to intestinally perfused oleate and tryptophan seen after extragastric vagotomy could be caused either by interruption of reflex paths between gut and pancreas or by interference with CCK release. Extragastric vagotomy reduced pancreatic responses to a meal and to 2-DG and subsequent truncal vagotomy caused still further reduction, possibly, at least in part, by depressing release of antral gastrin.
Alterations in hepatic chromatin template availability during infection
Authors: Earp HS
Published: December 2017

Hepatic chromatin was isolated from rats at various times after inoculation with either live or heat-killed bacteria. The chromatin was assayed under conditions that allow determination of the DNA template available to support in vitro transcription. Both a fulminant Diplococcus pneumoniae and a milder Salmonella typhimurium infection produced time-related increases in hepatic chromatin template availability when compared to chromatin isolated from rats inoculated with heat-killed bacteria. Both timing and magnitude of increased template availability correlated with the severity of the infection. The earliest change observed was a 50 percent rise in availability noted 4 h after inoculation with D. pneumoniae. This preceded the onset of fever, as well as other known heaptic consequences of systemic infection. After 24 h of infection the maximum rise of 90 percent occurred. Similar changes developed during S. typhimurium infection, but were slower in onset and smaller in magnitude. Adrenalectomy prior to infection enhanced the severity of the disease but markedly blunted the increase in template availability. The data are consistent with the hypothesis that systemic infection regulates the hepatic metabolic response to infection through transcriptional control and that a permissive or stimulatory action of glucocorticoids is involved in the increases in template availability effected.
Effects of graded solute diuresis on renal tubular sodium transport in the rat
Authors: Khuri RN , Strieder N , Wiederholt M , Giebisch G
Published: December 2017

Sodium transport was studied across proximal and distal tubules of rats undergoing progressive intravenous loading with either isomotic saline or urea (200 mosmol)-saline (100 mosmol) solutions. Free-flow as well as recollection micropuncture techniques were used, and tubular fluid (TF) samples were analyzed for inulin-14C and sodium (Na). With administration of progressively larger intravenous saline loads, the delivery of fluid and sodium into the distal tubule rose. Concomitantly, the normally observed decline of tubular sodium concentrations along the distal tubule became attenuated until it was abolished at the highest infusion rates of saline solutions. Absolute reabsorption rates of Na across the distal tubule increased in proportion to tubular flow rate, and no tubular maximum (Tm) was observed. It is suggested that the delivery of increased amounts of sodium to the normally unsaturated later parts of the distal tubule and the elevated tubular sodium concentration after saline loading account for the observed stimulation of distal tubular net sodium transport. The extent of transport stimulation is also subject to control by the amount of urea accumulation along the distal tubule. As the latter declines, sodium reabsorption is proportionately enhanced.
Free-feeding patterns of rats: effects of pyrogen and dietary protein content
Authors: Leung PM , Horwitz BA
Published: December 2017

Infusion of bacterial pyrogen (Priomen) was accompanied by an increase in body temperature, an increase in heat production, and a decrease in the voluntary food intake ofrats fed high-as well as low-protein diets. The magnitude of this pyrogen-induced depression of food intake was comparable for both diets. However, in rats fed high-protein diets, this decrease was additive to that normally seen following administration of such diets. These data indicate that the control of food intake cannot be explained in terms of a behavioral the more regulatory response.
Release of antirenin to human renin by anaphylactic shock or by antihypertensive agents
Authors: Haas E , Goldblatt H , Lewis L , Klick RL
Published: December 2017

In dogs that have had repeated intravascular injections of small doses of human renin, even for long periods, the development of antirenin to human renin in the blood has not been previously noted, and their pressor response (30 mmHg) to 1 U of human renin has remained unchanged for years. In such dogs, however, a profound, abrupt fall of the systemic blood pressure, due to an anaphylactic reaction to human renin, or to the infusion of depressor agents, such as Arfonad, histamine, or diazoxide, resulted in the appearance in the blood of an inhibitor specific for human renin. This inhibitor was suddenly released into the blood-stream from the tissues in which it presumably had been stored, and it persisted, in a relatively high concentration, in some animals for months. It did not occur in dogs that had not previously received many injections of human renin. This study has shown that the inhibitor has all of the properties of antirenin to human renin. It abolished the pressor response to hog, dog, and rat renin or to angiotensin and norepinephrine. It inactivated human renin, but not dog renin, duringits incubation with renin substrate to form angiotensin.
Reduced nicotinamide adenine dinucleotide and depolarization in neurons
Authors: Rodriguez-Estrada C
Published: December 2017

Activity of frog dorsal root ganglion neurons, evoked by dorsal root stimulation under aerobic conditions, produced a change in the level of reduced nicotinamide adenine dinucleotide (NADH) on the surface of this tissue. There was a decrease of NADH (oxidation), followed by an increase of NADH (reduction). Both changes were dependent on previous activity, and a critical time is required in order to observe a similar response. At the frequency and duration of stimulation used here, each stimulus evoked neuron depolarization as shown by recording from single cells. The NADH oxidation occurred in the respiratory chain and it was selectively blocked by Amytal. The NAD reduction was attributed to 3-phosphoglyceraldehyde dehydrogenase activity and it was blocked by iodoacetate. The NADH oxidation and NAD reduction were attributed to respiratory chain activity and aerobic glycolysis, both activated and deactivated by changes of phosphate potential (ATP/ADP + Pi). A low phosphate potential activates the respiratory chain and glycolysis; a high phosphate potential deactivates the respiratory chain and glycolysis.
Interaction of respiratory cell discharge patterns and spontaneous resporatory rate
Authors: Webber CL  , Peiss CN
Published: December 2017

Potentials from single respiratory cells in the inspiratory and expiratory populations of the medulla were recorded by extracellular microelectrodes in spontaneously breathing cats anesthetized with pentobarbital. Experiments were designed to follow alterations in single-cell discharge patterns after modification of the respiratory rate by either barbiturate depression or doxapram activation. Unit activity was quantitated by a computerized mathematical technique based on the sequential arrangement of interspike intervls. From this analysis several discharge parameters were derived which successfully quantitated initial (frequency increase), middle (frequency plateau), and terminal (frequency decrease) phases of spike activity. Discharge parameters were correlated with respiratory rate by the use of linear and curvilinear regression analyses. Theoretical discharge patterns for both inspiratory and expiratory populations were reconstructed at selected respiratory rates by interpolation from regression equations. These data, demonstrating average quantitative shifts in cell activation and deactivation phases as a function of respiratory rate, suggested several possibilities for the modulation of the respiratory frequency.
Bicarbonate and sodium reabsorption by the isolated perfused kidney
Authors: Besarab A , Silva P , Ross B , Epstein FH
Published: December 2017

The role of bicarbonate reabsorption and of transtubular chloride gradients in the bulk reabsorption of sodium and water by renal tubules can be tested in the isolated perfused kidney by perfusing with a medium from which bicarbonate has been omitted. Perfusion of the isolated rat kidney with an artificial medium in which bicarbonate is replaced by chloride results in a fall in fractional reabsorption of sodium from 97 to 84%. Stepwise restoration of bicarbonate concentration in the perfusion medium to 25 meq/liter is associated with a parallel recovery of sodium reabsorption to control levels. Inhibition of bicarbonate reabsorption with acetazolamide produces a slightly smaller reduction in sodium reabsorption (97-89%), an effect not seen in the absence of bicarbonate. Acetazolamide greatly increases phosphate excretion and free water clearance in a way consistent with suppression of proximal tubular reabsorption. By contrast, simple omission of bicarbonate from the perfusing medium does not alter phosphaturia or free water clearance. Reabsorption of bicarbonate appears to account for a fraction of sodium reabsorption roughly equivalent to the proportion of sodium associated stoichiometrically with bicarbonate in the glomerule filtrate. The data do not support the hypothesis that the development of a transtubular chloride gradient is critically important for the reabsorption of a large fraction of the glomerular filtrate.
Local ventricular repolarization changes due to sympathetic nerve-branch stimulation
Authors: Kralios FA , Martin L , Burgess MJ , Millar K
Published: December 2017

Functional distributions of individual cardiac nerves distal to the stellate ganglia were determined in 30 open-chest, anesthetized dogs by mapping sites of refractory-period shortening during stimulation of the nerves. On the right, recurrent cardiac nerve stimulation produced marked shortening of refractory periods in the interventricular septum, and lesser changes on the anterior heart surface. On the left, ventromedial cardiac nerve stimulation shortened refractory periods in a similar distribution, but changes were not marked as with the recurrent cardiac nerve. The other left-side nerve that produced repolarization changes, the ventrolateral cardiac nerve, produced marked refractory-period changes on the posterior heart surface. Its distribution showed little overlap with that of the ventromedial or recurrent cardiac nerves. T waves inverted in an electrocardiographic Y lead during recurrent cardiac and ventromedial cardiac nerve stimulation, while ventrolateral cardiac nerve stimulation increased the positivity of T waves in that lead. The cardiac distributions of individual nerves documented in this study provide an anatomical basis for localized alterations in ventricular electrophysiologic properties.
Cobalt inhibition of insulin secretion and calcium uptake by isolated rat islets
Authors: Henquin JC , Lambert AE
Published: December 2017

Cobalt (Co'++) inhibited glucose-, leucine-, and K'+-induced immunoreactive insulin (IRI)release by isolated rat islets. This inhibition of the insulinotropic effect of glucose was dose dependent, affected both phases of secretion, was very rapid, and was well reversible. It exhibited a kinetics similiar to that of Ca'++ omission, and the metal (2.5 mM) prevented Ca'++ reintroduction from restoring a normal rate of IRI release. Theophylline (2 mM) partially overcame the inhibitory effect of 0.5 mM Co'++, but not that of 2.5 mM. Glucose-induced secretion was lessmarkedly reduced by 0.5 mM Co'++ in the absence of Mg'++ or in the presence of 7.5 mM Ca'++. Even at 12.5 mM, the metal did not alter glucose oxidation by theislets. By contrast, Ca uptake by islet cells was reversibly diminished (55%) in the presence of 1.25 mM Co'++. Calcium influx (measured after 2.5 min) was aslo reduced by Co'++ to a degree that did not change after longer incubation periods. It is concluded that Co'++ inhibits IRI release mainly through an antaognistic action on Ca entry in beta cells.
Dissociation of Na-K-ATPase specific activity and net reabsorption of sodium
Authors: Fisher KA , Welt LG , Hayslett JP
Published: December 2017

Prevoius studies have suggested that the increase in specific activity of Na-K-ATPase in renal tissue during treatment with glucocorticoids occurred as a result of aconcurrent rise in net tubular reabsorption of sodium. Since recent data have indicated a specific effect of glucocortiocoids on epithelial cells, experiments were performed to determine whether enzyme activity and net sodium reabsorption could be dissociated.Evidence is provided demonstrating that base-line specific activity of Na-K-ATPase in rat renal cortex and outer medulla does not correlate directly with net sodium reabsorption since enzyme activity did not change after a chronic reduction in glomerularfiltration rate and the rate of sodium reabsorption. Further studies showed a markedrise in Na-K-ATPase after 4 days of treatment with methylprednisolone despite a fall in sodium absorption. These results suggest a direct effect of glucocorticoids onrenal Na-K-ATPase and illistrate the difficulty in assigning a transport role tothis enzyme from the correlation of specific activity with rates of net electrolyte transport.
Phospholipase A2 in experimental hypertension
Authors: Zachariah NY , Smeby RR , Sen S , Bumpus FM , Singh C
Published: December 2017

An assay method has been developed to measure phospholipase A2 (PLA2) in ratserum and to study the possible role of this enzyme in experimental hypertension. Experiments with rat serum following 48 h of bilateral nephrectomy indicated a decrease inPLA2 activity, suggesting that kidneys might be playing an important role in regulating serum PLA2 activity and that kidneys might be a source of this enzyme. Experiments with renal hypertensive rats, spontaneously hypertensive rats, and rats receiving a low-salt diet demonstrated that a decrease in PLA2 activity was found only in those conditions in which elevated plasma renin activity was accompanied by elevated blood pressure. When elevated plasma renin activity was not accompanied by elevated blood pressure, serum PLA2 activity was unchanged. These observations represent the first biochemical separation between conditions of elevated plasma renin activity without an increase in blood pressure and conditions of elevated plasma renin activity with an increasein blood pressure.
In vivo measurement of brain glucose transport and metabolism employing glucose- -11C
Authors: Raichle ME , Larson KB , Phelps ME , Grubb RL  , welch MJ , Ter-Pogossian MM
Published: December 2017

The radiopharmaceutical glucose--11C was used in vivo measurement of brain-glucose transport kinetics and metabolism in the rhesus monkey. Radiotracer was injected intravenously as a bolus. Radioactivity was continuously recorded from the head and from the arterial blood via an indwelling peripheral artery catheter for a collectionperiod of 2-3 min. To correct the reading obtained from the head for radioactivitycontained in blood, a second intravenous injection of the vascular tracer -15O-labeled carboxyhemoglobin was used. The method was tested in nine phencyclidine-anesthetized monkeys in which cerebral glucose metabolism (CMRGlc) was simultaneously measured by our method and by a standard method emplying the Fick principle. A highlysignificant correlation was found between the two methods of measuring CMRGlc (r =0.929). In addition, our model predicted a ratio of forward-to-reverse glucose flux across the blood-brain barrier (BBR) (1.37 plus or minus 0.23 SD), the brain-to-bloodglucose concentration ratio across the BBB (0.633 plus or minus 0.14), the relative tissue free-glucose space (17 plus or minus 7%), the brain free-glucose concentration (13.6plus or minus 8.5 mg/100 g of tissue), and the brain free-glucose turnover time (2.96 plus or minus 1.98 min). author
Interrelationship of chlorothiazide and parathyroid hormone: a micropuncture study
Authors: Quamme GA , Wong NL , Sutton RA , Dirks JH
Published: December 2017

Sodium and calcium are normally reabsorbed in parallel in the renal tubule. Both parathyroid hormone (PTH) and thiazide diuretics may influence this relationship. This study was designed to show whether the dissociation of Na from Ca transport produced by thiazides is dependent upon the presence of PTH. Hydropenic thyroparathyroidectomized (TPTX) dogs were given chlorothiazide alone and together with PTH. Chlorothiazide alone significantly increased fractional excretion of sodium (0.5 +/- 0.3-5.6 +/- 0.3%) and calcium (0.74 +/- 0.18-1.4 +/- 0.24%). However, the Ca/Na excretion ratio fell markedly from 1.57 to 0.24%. Micropuncture revealed this dissociation to occur at the distal tubule. Proximal reabsorption of water, sodium, and calcium were inhibited to an equal extent. However, distal fractional sodium reabsorption fell 10% whereas calcium reabsorption remained unchanged following chlorothiazide administration in TPTX animals. When phosphaturic doses of PTH were administered with chlorothiazide, no significant changes were observed in calcium or sodium reabsorption. It is concluded that PTH plays no role in the dissociation of sodium from calcium reabsorption resulting from acute chlorothiazide administration.
Thyroid hormone-induced changes in body temperature and metabolism during exercise in dogs
Authors: Kaciuba-Uscilko H , Greenleaf JE , Kozlowski S , Brzezinska Z , Nzar K , Ziemba A
Published: December 2017

Changes in serum total thyroxine concentration (TT4) and the effects of thyroxine (T4) and 3,5,3'-triiodothyronine (T3) injection on plasma free fatty acid (FFA) level and rectal temperature (Tre) responses were measured in six dogs at rest and during 1 h of submaximal treadmill exercise. At rest there were no increases in FFA level or Tre up to 72 h after thyroid hormone treatment. During exercise, 5 h after a single T4 injection (0.1 mg/kg), there was a) a significant increase in TT4, although the resting level was markedly elevated, and b) a significant increase in FFA concentration and Tre above control values. Seventy-two hours after T4 injection there was a similar increase in TT4 during exercise and both FFA and Tre levels were greater than 5-h values. The elevated Tre was not associated with increased plasma Na+, K+, or osmotic concentrations. Compared with T4 data, T3 injection (0.1 mg/kg) resulted in greater increases in FFA level and Tre during exercise; two animals reached 43.1 degrees C. There were no significant differences in the respiratory exchange ratio (R) or O2 uptake between the control and T3 experiments. It was concluded that thyroid hormones markedly enhance FFA mobilization and elevated Tre during exercise, but not a rest. The hyperthermic response appears to be due to an increase in the level of regulated body temperature rather than to a depression of heat dissipation.
Water and electrolyte transport by rabbit esophagus
Authors: Powell DW , Morris SM , Boyd DD
Published: December 2017

The nature of the transmural electrical potential difference and the characteristics of water and electrolyte transport by rabbit esophagus were determined with in vivo and in vitro studies. The potential difference of the perfused esophagus in vivo was -28 +/- 3 mV (lumen negative). In vitro the potential difference was -17.9 +/- 0.6 mV, the short-circuit current 12.9 +/- 0.6 muA/cm2, and the resistance 1,466 +/- 43 ohm-cm2. Net mucosal-to-serosal sodium transport from Ringer solution in the short-circuited esophagus in vitro accounted for 77% of the simultaneously measured short-circuit current and net serosal-to-mucosal chloride transport for 14%. Studies with bicarbonate-free, chloride-free, and bicarbonate-chloride-free solutions suggested that the net serosal-to mucosal transport of these two anions accounts for the short-circuit current not due to sodium absorption. The potential difference and short-circuit current were saturating functions of bathing solution sodium concentration and were inhibited by serosal ouabain and by amiloride. Thus active mucosal-to-serosal sodium transport is the major determinant of the potential difference and short-circuit current in this epithelium.