bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effects of Ouabain on Atrioventricular Junctional Automaticity and Conductivity Studied in the Dog
Authors: Elharrar Victor , Nadeau Réginald A. , Roberge Fernand , Porlier Gérald A. , Pelletier Claude
Published: April 2011

In the anesthetized dog, the effects of ouabain injected intravenously and directly into the atrioventricular (A-V) node artery were studied. Automaticity within the A-V junction was decreased after a dose of ouabain, 30 μg/kg given intravenously (i.v.), whereas automaticity of ventricular specialized fibers was increased after a dose of 40 μg/kg i.v. The decrease of automaticity within the A-V junction was accompanied by an increased duration of the functional refractory period of this structure and by a prolongation of conduction time through the A-V junction as determined from the His bundle electrogram.
Effects of a High Cholesterol–Oil Diet for Rabbits on Concentrations of Heparin and Total Sulfated Mucopolysaccharide in Aorta and Other Tissues Measured by Microelectrophoresis
Authors: Sue T. K. , Jaques L. B.
Published: April 2011

Rabbits were fed a high cholesterol–oil diet for 13 weeks. The amounts of total sulfated mucopolysaccharides and heparin in aorta, heart, skin, and small and large intestine were determined by microelectrophoresis. Aortic lipoprotein lipase activity, serum cholesterol, and triglycerides were also measured. The results showed that quantities of total sulfated mucopolysaccharides, heparin, and lipoprotein lipase activity increased markedly in aortas but were without change in other tissues in the rabbits on the experimental diet. There was a high correlation between lipoprotein lipase activity and concentrations of both heparin and total sulfated mucopolysaccharides in aorta, and also between concentrations of heparin and total sulfated mucopolysaccharides in aorta and serum levels of triglyceride and cholesterol.
Cardiovascular Effects of Marihuana in Man
Authors: Clark S. C. , Greene C. , Karr G. W. , MacCannell K. L. , Milstein S. L.
Published: April 2011

Twenty-eight subjects, matched by sex and Cannabis experience, received by controlled inhalation under single- and double-blind conditions 600 mg marihuana placebo and marihuana. Forearm, venous and arterial pressures, forearm blood flow, and heart rate were recorded while supine. Derived functions such as "dp/dt", regional arterial resistance, and venous compliance were calculated from these variables. (1) Placebo produced no intoxication or consistent physiological responses. (2) Marihuana produced intoxication in all Cannabis-experienced and half the non-experienced subjects. (3) Cardiovascular responses occurred in response to marihuana in the absence of intoxication, indicating that they were not psychogenically mediated. (4) Inhibition of vagal tone may contribute to the tachycardia seen with marihuana. (5) Reflexly mediated sympathetic responses may be muted in the presence of marihuana.
Lack of Interaction between Norepinephrine or Histamine and Theophylline on Cardiac Cyclic AMP
Authors: McNeill John H. , Coutinho F. Edmund , Verma Subhash C.
Published: April 2011

The hypothesis that theophylline can enhance the cardiac effects of norepinephrine and histamine by inhibiting phosphodiesterase was tested in isolated perfused hearts of rats and guinea pigs. Theophylline did enhance the inotropic and phosphorylase-activating effect of both amines. Cyclic AMP, increased by the injection of the amines, was not further increased when the hearts were perfused concomitantly with theophylline. When theophylline was injected into the heart, an increase in contractility and phosphorylase a was noted but cyclic AMP values were not affected. The data do not support phosphodiesterase inhibition as the mechanism by which theophylline produces its cardiac effects.
A Functionally Important Feature of the Distribution of the Olivo–Cerebellar Climbing Fibers
Authors: Courville J. , Faraco-Cantin F. , Diakiw N.
Published: April 2011

The olivo–cerebellar projection has been demonstrated by injections of small volumes of tritiated l-leucine in the inferior olive. A strictly contralateral projection to the cerebellar cortex has been found. Labelling of terminal fibers in the molecular layer is restricted to the paravermian and lateral regions of cortex after an injection of the central region of the olive. The distribution presents a very striking feature: the label is distributed along sagittal bands about 0.4 mm wide interrupted by empty spaces of the same width. It is suggested that an extra-olivary source provides the climbing fibers distributed in these spaces.
Effect of Ablation of the Subfornical Organ on Water Intake Elicited by Systemically Administered Angiotensin-II
Authors: Abdelaal A. E. , Assaf S. Y. , Kucharczyk J. , Mogenson G. J.
Published: April 2011

The effect of electrolytic lesions of the subfornical organ on water intake induced by the continuous infusion of angiotensin-II through a chronic jugular cannula was studied. Lesions of the subfornical organ significantly reduced but did not abolish the elicited drinking. These results support the hypothesis that the subfornical organ is a receptor site for angiotensin-II but also suggest that this may not be the only site of receptors.
Thermal Balance and Survival Time Prediction of Man in Cold Water
Authors: Hayward J. S. , Eckerson J. D. , Collis M. L.
Published: April 2011

Metabolic rates and rectal temperatures were continuously monitored for humans immersed in cold ocean water (4.6–18.2 °C) under simulated accident conditions. The subjects wore only light clothing and a kapok lifejacket while either holding-still or swimming. While holding-still, metabolic heat production (Hm, kcal∙min−1) was inversely related to water temperature (Tw, °C) according to the equation Hm = 4.19−0.11Tw. This thermogenic response pattern is shown to be similar to that for exposure to air of the same temperature when air velocity is just over 5 m.p.h. (2.24 m/s).The thermogenic response was one-third efficient in balancing the calculated heat loss in cold water, resulting in hypothermia at a rectal temperature cooling rate (C, °C∙min−1) dependent on water temperature (Tw, °C) according to the relation C = 0.0785−0.0034Tw.Although swimming increased heat production to 2.5 times that of holding-still at 10.5 °C water temperature, cooling rate was 35% greater while swimming.A prediction equation for survival time (ts, min) of persons accidentally immersed in cold water (Tw, °C) has the form ts = 15 + 7.2/(0.0785−0.0034 Tw), based on the findings of this study, and it is compared to pre-existing models.
Extrahepatic Distribution of Sulfobromophthalein
Authors: Klaassen Curtis D.
Published: April 2011

Plasma clearance of sulfobromophthalein (BSP) is widely used as a measure of hepatic function. Its validity depends upon its exclusive elimination from the body via bile. For example, in the present study, when BSP was administered intravenously (i.v.) to rats at four different doses (18.75, 37.5, 75, and 150 mg/kg), less than 0.5% of each dose was excreted into the urine and between 70 and 85% was excreted into the bile within 6 h after administration. It has been assumed that the distribution of BSP is limited to the blood and liver with very little appearing in other tissues. When we measured the amount of BSP in the plasma, liver, and bile 10 min after the i.v. administration of either a high (150 mg/kg) or a low (18.75 mg/kg) dose of BSP, only 60% of the dose was accounted for. The concentration of BSP and 125I-labelled albumin (RISA) was measured in various tissue samples 10 min after administration of 17.5 or 150 mg of BSP or RISA per kilogram. More BSP was found in all tissues than was contained in the plasma entrapped therein. Thus, the distribution of BSP is not limited to the liver and plasma. During excretion BSP leaves other tissues (kidney, spleen, lung, etc.) and is ultimately excreted into the bile.
Withdrawal Rates of DDT from Chickens Treated with Diphenylhydantoin
Authors: Polin Donald , Ringer Robert K.
Published: April 2011

Male and female chickens of a broiler-type strain were fed, from 1 day old to 5 weeks of age, diets containing 0, 2.5, or 15.0 p.p.m. (mg/kg) 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (p,p′-DDT). Then the diets with pesticide were withdrawn and the chickens were fed dietary levels of diphenylhydantoin (DPH) at 0,100, or 250 p.p.m. Adipose-tissue and liver samples were obtained on days 0, 10, 20, and 30 following withdrawal of diets with pesticides to determine DPH effect on DDT, 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE), and 1,1-dichloro-2,2-bis(p-chlorophenyl)ethane (DDD) levels. DPH had no effect on the concentration of DDT and DDE in adipose tissue; their levels declined at a rate having a half-life value of 16 days. DDD was not detected in adipose tissue. DDT accounted for 87% of the adipose tissue residues on day 0, but 66% of the residues at day 30. DPH had no effect on the concentrations of DDT and DDE in livers of chickens fed 15.0 p.p.m. DDT, but did significantly reduce the levels of DDD by 28 and 54% for levels of 100 and 250 p.p.m. DPH, respectively. The similarity of these data to studies on dairy cows and humans, and the dissimilarity to data from rat studies were discussed.
Natriuresis Following Fourth Ventricle Perfusion with High-sodium Artificial CSF
Authors: Passo S. S. , Thornborough J. R. , Rothballer A. B.
Published: April 2011

Perfusion of the fourth cerebral ventricle with high-sodium artificial cerebrospinal fluid was found to result in an increase in urinary sodium excretion in anesthetized cats. The natriuresis was accompanied by an increase in blood pressure and glomerular filtration rate. However, in animals with the changes in blood pressure and glomerular filtration rate prevented by alpha-adrenergic blockade (phenoxybenzamine), the increase in urinary sodium excretion persisted. The data suggest the presence of a neural mechanism in the vicinity of the fourth ventricle sensitive to cerebrospinal fluid sodium levels and capable of affecting urinary sodium excretion independent of changes in blood pressure or glomerular filtration rate. The possible role of the area postrema and adjacent medulla is considered.
Renal Transport of Organic Acids and Bases in Genetically Obese Mice
Authors: Johnson Jenny T. , Kaplan Murray L. , Leveille Gilbert A. , Hook Jerry B.
Published: April 2011

Accumulation of p-aminohippurate (PAH) and N-methylnicotinamide (NMN) by renal cortical slices was used to estimate transport capacity for organic anions and cations, respectively. In a previous study, renal organic anion transport appeared to be selectively depressed in animals rendered obese by high fat feeding. However, the effects of obesity could not be discretely separated from the effects of the 60% fat diet used to produce the obesity. Genetically obese hyperglycemic mice provided a model to determine the effect of obesity on renal transport systems without the complications due to diet. Accumulation of both PAH and NMN was depressed in renal cortical slices from genetically obese mice. Addition of plasma from thin or obese animals increased PAH accumulation by slices from thin animals. Accumulation by slices from obese animals was unaffected by addition of plasma. Oxygen consumption with acetate in the medium was less in kidneys from obese mice than kidneys from thin mice. Thus, in addition to inhibition of transport capacity, renal cortex of genetically obese mice has a biochemical defect that prevents response to stimulators. It is concluded that several renal functions are depressed in the genetically obese hyperglycemic mouse. Whether the depressed function results from the obesity or is concomitant with the gene for obesity is as yet undetermined.
Correlation of Structural Changes at Different Levels of the Jejunal Villus with Positive and Negative Net Water Transport in Vivo and in Vitro
Authors: McElligott T. F. , Beck I. T. , Dinda P. K. , Thompson S.
Published: April 2011

Experiments were done for identification and localization of certain structural changes at different levels of jejunal villus of the hamster during positive and negative water transport across the intestine in vivo and in vitro. Positive transport occurred when the mucosal surface of the intestine was bathed (in vitro experiments) or perfused (in vivo experiments) with isotonic Krebs–Ringer bicarbonate solution containing 10 mM glucose, and negative water transport was achieved by rendering this solution hypertonic with 150 mM mannitol. Results indicate that during positive net water transport, the intestine in vivo transported more fluid and exhibited a more conspicuous dilatation of the lateral intercellular spaces (L.I.S.) than did the in vitro preparation. Dilatation of the L.I.S. in both preparations was present only in the apical part of the villus, suggesting that this is the principal site of water absorption. When the mucosal solution was made hypertonic with mannitol, the L.I.S. in the in vivo intestine totally collapsed, whereas in the in vitro intestine these spaces remained open very slightly. These morphological changes correspond well with our finding that in the presence of the hypertonic mucosal solution there was a greater net negative water transport in vivo than in vitro. Incubation of the intestine in the isotonic mucosal solution produced subnuclear swelling of the mid-villus epithelial cells, and this morphological change was associated with an increase in the water content of the tissue. Perfusion of the in vivo intestine with the isotonic solution produced neither the swellings nor the increase in water content of the tissue. In the presence of hypertonic mucosal solution there was a water loss from the tissue both in vivo and in vitro, and these swellings were not observed. These results are discussed in relation to intestinal sugar transport and to the maturity of the epithelial cells, and it is concluded that transport studies on in vitro preparations may provide valid information on a qualitative basis, if not on a strictly quantitative basis.
The Effect of Hemicholinium-3 on Choline and Acetylcholine Levels in a Sympathetic Ganglion
Authors: Khatter J. C. , Friesen A. J. D.
Published: April 2011

Preganglionic stimulation of the cat's superior cervical ganglion in the presence of hemicholinium-3 (HC-3) produced the expected depletion of acetylcholine (ACh) stores, but failed to cause a corresponding reduction in the choline content. These results suggest that either HC-3 possesses an intracellular site of action or that in lower doses it selectively inhibits a specialized choline transport system in cholinergic nerves. At a dose of 2 mg/kg, HC-3 probably blocked ACh synthesis completely in ganglia stimulated at 20 Hz. Under these conditions, there was a rapid depletion of ACh to about 50% of control levels during the first 5 min of stimulation and thereafter the rate of decline in ACh levels proceeded at a much slower pace. Since the 2 mg/kg dose of HC-3 did not raise plasma choline concentrations, it may be assumed that non-specialized choline transport systems in other tissues were not significantly inhibited by this dose of HC-3. However, when the dose of HC-3 was increased to 4 mg/kg, plasma choline levels increased by 58%.
Effets de la thymectomie néonatale sur la teneur en magnésium du plasma et de quelques tissus du rat
Authors: Deschaux P. , Binimbi-Massengo  , Charnot Y. , Fontanges R.
Published: April 2011

White rats were thymectomized neonatally. After 60 days, no alteration was noted in the plasma or testis magnesium level. On the other hand, a marked decrease was observed in the magnesium content of muscle (−23%) and of bone (−19%). The injection of thymosin reversed these changes. These findings suggest that a correlation between the thymus and the muscle is exerted by a protein factor (thymosin), and that the thymus may act on sex glands through an indirect pathway.
Oxygen and Effective Vascular Compliance in Acute Heart Failure
Authors: Larochelle P. , Ogilvie R. I.
Published: April 2011

The effect of hypoxemia on total vascular compliance was studied in anesthetized dogs using a venous bypass technique. Cardiac output was kept constant with an extracorporeal pump and respiration controlled to maintain normocapnia. When nitrogen was added to the respired gas to produce an arterial [Formula: see text], total vascular compliance was rapidly and significantly reduced to 0.93 ml (mm Hg)−1 kg−1 with incomplete recovery to baseline values of 1.30 ± 0.06 ml (mm Hg)−1 kg−1 during subsequent ventilation with 100% oxygen. Acute heart failure was induced by gradual aortic constriction. Ventilation with 100% oxygen failed to prevent a gradual reduction in total vascular compliance to 0.86 ml (mm Hg)−1 kg−1 from a baseline value of 1.23 ± 0.06 ml (mm Hg)−1 kg−1. Ventilation with 100% oxygen following the reduction in vascular compliance during acute heart failure also failed to significantly alter this parameter. Thus, improvement of arterial oxygen tension in patients with acute heart failure would be beneficial in providing greater oxygen delivery to the tissues without abolishing a compensatory mechanism of reduced vascular compliance which attempts to maintain a cardiac filling gradient of pressure.
Stability and Biological Activity of Catecholamines and 5-Hydroxytryptamine Immobilized to Sepharose and Glass Beads
Authors: Yong Man Sen , Richardson John B.
Published: April 2011

[14C]Noradrenaline, [14C]adrenaline, and 5-[14C]hydroxytryptamine were complexed to several types of Sepharose derivatives through an amide or a diazo linkage. Complexes were also made with arylamine glass beads through a diazo linkage. After the reaction the complexes were extensively washed with distilled water or dilute HCl or both, plus other solvents. Radioactivity appeared in the storage solutions and the amount increased with time. When initial low levels of release were achieved by extensive washing, the addition of a different solvent produced a marked increase in release. The biological activity of these complexes was tested on isolated rabbit aortic strips and rat fundus strips. All complexes caused the tissues to contract. The biological activity, however, closely paralleled the release of the ligands from the complexes and the release of ligand was demonstrated through the use of oil immersion and dialysis sac. These data do not support the recent claims that catecholamines bound to glass beads exert their pharmacological effects as covalently bound complexes on isolated tissue. The lack of stability of these complexes indicates the need for caution in drawing conclusions as to the site or the mechanism of action of immobilized catecholamines and other drugs.
Effects of Age and of Fasting on the Responsiveness of the Insulin-Secreting Mechanism of the Islets of Langerhans to Glucose
Authors: Coddling J. A. , Kalnins A. , Haist R. E.
Published: April 2011

Insulin responsiveness to glucose of isolated islets of Langerhans was studied in 'younger' and 'older' rats after feeding and fasting for various lengths of time. In 'younger' rats, after prolonged fasting (168 h) the threshold for glucose-stimulated insulin secretion was increased. This was not evident in islets from 'younger' rats fasted for 48 or 89 h. Reductions in increments of insulin secretion with increments in glucose, in the maximum insulin secreted and in the total extractable insulin of the islets were apparent after fasting for 48, 89 and 168 h as compared with islets from fed rats. In 'older' rats, prolonged fasting caused an increase in the threshold for glucose-stimulated insulin secretion, reduced incremental insulin secretion, reduced maximum insulin secretion and reduced total extractable insulin. However, the responses of islets from fed 'older' rats were similar to those of fasted (168 h) 'younger' rats. The threshold levels were similar, and there were no significant differences between increments in insulin secretion, maximum insulin secretion and insulin content of the islets. These experiments show that the responsiveness of islets of Langerhans in rats can be altered by age and fasting.
The Development of Sympathetic Innervation and the Functional State of the Cardiovascular System in Newborn Dogs
Authors: Gauthier Pierre , Nadeau Réginald A. , Champlain Jacques de
Published: April 2011

The present study in dogs indicates that the peripheral sympathetic fibers develop mostly after birth and reach a full maturity at about 2 months of life. The norepinephrine content of the heart, spleen, intestine, salivary glands, and adrenal glands increased from birth to 56 days of age. In contrast, the content of the stellate ganglia decreased during this period. In most of the organs studied, the uptake of [3H] norepinephrine developed in parallel with the norepinephrine content, except in the right atrium and salivary glands where it was fully developed soon after birth. During development, the systemic blood pressure increased from 40 to 100 mm Hg. Bilateral adrenal vessel clamping failed to induce a fall in blood pressure in growing dogs which indicates that the adrenal medulla or the baroreceptors did not fully compensate for the lack of peripheral sympathetic fibers and for the lower blood pressure in newborn animals. Although cardiac norepinephrine content was still very low in 10-day-old animals, cardiovascular responses to direct and reflex sympathetic stimulation were similar to those observed in 56-day-old animals. These results indicate that the sympathetic nervous system becomes functional before the fibers reach their full maturity.
An Efferent Effect on a Rhythmic Response in the Frog Retina
Authors: Kline Loren W. , Pickering S. G.
Published: April 2011

Extracellular recordings made from class III ganglion cells demonstrated a rhythmic bursting firing pattern in response to the offset of a mesopic level stimulus of 15, 30, and 90-s duration. The average bursting frequency was found to be 12.8 ± 0.3 bursts per second. The bursts of action potentials had a duration of 0.047 ± 0.002 s and separated by silent periods of 0.028 ± 0.006 s. When a reversible cold block was applied to the optic chiasma, the rhythmic bursting pattern was replaced with a firing pattern that appeared random, indicating that efferent fibers to the retina might regulate the rhythmic response.
Water, Cations, and Norepinephrine Content of Cardiovascular Tissues of Unilaterally Nephrectomized Dogs Treated with Deoxycorticosterone and NaCl
Authors: Constantopoulos George , Genest Jacques , Kusumoto Miyako , Rojo-Ortega José-Manuel
Published: April 2011

Deoxycorticosterone pivalate (2.5 mg/kg) given intramuscularly on four occasions 10–15 days apart over a period of 45 days to unilaterally nephrectomized adult male mongrel dogs, receiving as drinking solution 0.9% NaCl in 5% dextrose, resulted in an average sustained rise in the mean arterial blood pressure of 30 mm Hg (1 mm Hg = 133 N/m2) in 60% of the animals. Hypertensive dogs had in their arterial tissues generally more sodium, potassium, magnesium, and calcium than the similarly treated but non-hypertensive dogs, but compared to the tissues of operated untreated or unoperated normotensive dogs, only sodium and calcium were significantly higher. The dogs who were similarly treated but did not develop hypertension had in their arterial tissues less sodium, potassium, and magnesium than operated untreated or unoperated normotensive dogs. Norepinephrine content in the branches of mesenteric arteries of all deoxycorticosterone- and NaCl-treated animals, irrespective of their blood pressure, was significantly lower, and in the myocardium significantly higher, than either the unoperated normotensive or operated but not further treated dogs. It is concluded, therefore, that in deoxycorticosterone + NaCl treatment the dogs which developed hypertension had more arterial sodium, potassium, magnesium, and calcium than those who were similarly treated but remained within the limits of normal blood pressure, and that there was no difference between hypertensive and non-hypertensive dogs in regard to their cardiovascular norepinephrine content.
Factors Determining the Decay of K+ Potentials and Focal Potentials in the Central Nervous System
Authors: Krnjević K. , Morris M. E.
Published: April 2011

Post-tetanic undershoots in extracellular focal potential (ΔV) and K+ potential (EK) can be recorded in the cuneate nucleus and dorsal horn of Dial-anaesthetized or decerebrate cat. They are seen best at depths where the largest ΔEK and ΔV are recorded and they increase with the frequency and duration of stimulation. The very different time courses of undershoots of ΔV and ΔEK indicate two hyperpolarizing influences: first, electrogenic pumping, and later, a reduced external K+ concentration. The importance of active K+ removal in determining the amplitude and duration of ΔEK and ΔV is illustrated by their marked potentiation (as well as the disappearance of post-tetanic undershoots) induced by a lowering of blood pressure or local application of strophanthidin.
Effect of Succinylcholine on Responses of Neurons in the Motor Cortex to Natural Activation of Muscle Spindle Primary Endings
Authors: Wong Y. C. , Kwan H. C. , Murphy J. T.
Published: April 2011

In locally anesthetized cats, the effects of intravenous administration of succinylcholine (SCh) in sub-paralytic dosages on the responses of single neurons in motor cortex to small dynamic muscle stretches were studied. A large transient enhancement of these cortical responses with a time course corresponding to the peripheral action of SCh on muscle spindles was observed. This finding is discussed in terms of the hypothesis that muscle spindle primary endings may activate projections to motor cortex.
The Effect of Metoclopramide on Inhibition Induced by Purine Nucleotides, Noradrenaline, and Theophylline Ethylenediamine on Intestinal Muscle and on Peristalsis in Vitro
Authors: Okwuasaba Francis K. , Hamilton John T.
Published: April 2011

Metoclopramide (N-(diethylaminoethyl)-2-methoxy-4-amino-5-chlorobenzamide) (Mcp) at concentrations of 0.1 and 1.0 μM partially and significantly reduced the relaxations induced by adenosine 5′-triphosphate (ATP), adenosine diphosphate (ADP), and adenosine, was without effect on theophylline ethylenediamine whilst significantly potentiating noradrenaline on the atropine-pretreated (0.1 μM) taenia coli, rabbit ileum, and rat duodenum. Mcp (1.0 μM) decreased the inhibitory effects of ATP, ADP, and adenosine on peristalsis induced in the isolated guinea-pig ileum by a constant increase in intraluminal pressure, did not affect inhibition due to theophylline ethylenediamine, whilst it potentiated inhibition of peristalsis due to noradrenaline. It is proposed that this effect of Mcp may be a specific antagonistic action on receptors sensitive to the putative purinergic transmitter, ATP and ADP, and may be partly responsible for its observed facilitatatory action on peristalsis.
Epileptiform Seizures in Domestic Fowl. V. The Anticonvulsant Activity of Δ9-Tetrahydrocannabinol
Authors: Johnson D. D. , McNeill J. R. , Crawford R. D. , Wilcox W. C.
Published: April 2011

The anticonvulsant activity of Δ9-tetrahydrocannabinol (Δ9-THC) has been determined against seizures induced in epileptic chickens by intermittent photic stimulation (IPS) and in epileptic and nonepileptic chickens by Metrazol. Intravenous administration of the drug reduced both the severity and incidence of seizures evoked by IPS in epileptic chickens. This anticonvulsant action was accompanied by a reduction in frequency of inter-ictal slow-wave high-voltage electroencephalographic activity and by the absence of spiking during IPS. Δ9-THC did not affect the incidence of Metrazol-induced seizures in epileptic or nonepileptic chickens.
Relative Influence of Carotid Baroreceptors and Muscle Receptors in the Control of Renal and Hindlimb Circulations
Authors: Pelletier Conrad L. , Shepherd John T.
Published: April 2011

In vagotomized dogs, a comparison was made of the relative ability of the carotid baroreceptors and of the receptors in skeletal muscles to cause constriction of the renal and hindlimb resistance vessels. With kidney and hindlimb perfused at constant pressure a decrease in pressure in the carotid sinuses from 250 to 40–45 mm Hg (1 mm Hg = 133 N/m2) caused the respective blood flows to decrease by 19 ± 6% and 80 ± 4% (mean ± SE), and stimulating muscle receptors with capsaicin caused a further decrease of 49 ± 9% and 4 ± 2%, respectively. With perfusion at constant flow, the baroreflex caused an increase of 34 ± 4 mm Hg in the renal perfusion pressure and of 99 ± 10 mm Hg in the hindlimb; capsaicin caused further increases of 203 ± 17 and 35 ± 9 mm Hg, respectively. These responses were abolished by sympathectomy. Capsaicin injection increased mean renal sympathetic nerve activity by 111 ± 16% over the maximal impulse frequency recorded when the carotid sinus pressure was 40–45 mm Hg. Thus, withdrawal of the restraint exerted by the carotid baroreceptors on the pool of central neurons controlling the vascular beds of the hindlimb and kidney leads to near maximal constriction of the resistance vessels in the former but not the latter; with strong activation of muscle receptors, near maximal constriction occurs in both beds.
Effect of Various Sterols on the 22Na Permeability and Fluidity of Phospholipid Bilayer Membranes
Authors: Singer M. A. , Wan J. K. S.
Published: April 2011

Sodium-22 efflux was measured in multilamellar liposomes composed of egg lecithin, dicetylphosphate, and various sterols. In a parallel series of experiments a spin labelled fatty acid ester was incorporated into similar vesicles and the molecular motion of the spin label monitored by electron spin resonance spectroscopy. Spin label mobility was used as a measure of phospholipid hydrocarbon chain motion. There was a poor correlation between the effects of these sterols on sodium permeability and their effects on the motion of the lipid chains. It is postulated that sterols alter sodium transport not only through a reduction in the motional freedom of membrane lipids, but also through changes in the partitioning of sodium between membrane and aqueous phases.
Effects of Secretin on Insulin Secretion and Glucose Tolerance
Authors: Dupré J. , Chisholm D. J. , McDonald T. J. , Rabinovitch A.
Published: April 2011

Effects of intravenous (IV) infusion of secretin during IV infusion of glucose were examined in normal men. Secretin was administered according to three schedules: with each schedule a comparable priming dose was delivered in the first minute, but this was followed by a maintained (120 min) infusion of secretin at a relatively high rate, or by maintained infusion at one-third that rate, or by brief (15 min) infusion at the lower rate. The lower infusion rate produced increments in secretin in the blood within the range attainable during endogenous secretion. By comparison with effects of glucose alone each secretin infusion enhanced the increments of immunoreactive insulin in the blood. Enhancement of the early release (0–5 min) of insulin was similar with each type of secretin infusion, but the integrated changes in insulin levels through the total infusion period were related to the total doses of secretin. With each dose of secretin glucose tolerance was improved but the three mean glucose curves observed during infusions of secretin were not distinguishable from one another in spite of widely different integrated insulin responses. Secretin did not modify suppression of immunoreactive glucagon or free fatty acids in the blood during hyperglycemia. The results suggest that the effect of continuous administration of secretin on glucose tolerance is not simply related to its integrated insulinotropic action. It is suggested that the effect may be highly dependent on enhancement of insulin secretion early in the response to glycemia, or that it may be due to effects of secretin on glucose production or disposal which are not mediated by insulin.
Factors Affecting Ciliary Beat Frequency in the Intrapulmonary Airways of Rats
Authors: Melville G. Norris , Iravani J.
Published: April 2011

The influence of drugs on ciliary beat frequency in the intrapulmonary airways of rats was studied in vitro. Sympathomimetic drugs significantly increased the ciliary beat frequency. Acetylcholine, pilocarpine, aminophylline, prednisolone, potassium iodide, and ammonium chloride also caused cilioexcitation, though to a lesser degree. Phentolamine, 5-hydroxytryptamine, histamine, and acetylcysteine caused an apparent cilioinhibition. However, histamine in high doses also caused an incoordination of ciliary beat. Codeine and phenobarbital were slightly cilioexcitatory in low concentrations and ciliodepressive at higher concentrations.
Radioimmunoassay Studies of Intestinal Calcium-binding Protein in the Pig. II. The Distribution of Intestinal CaBP in Pig Tissues
Authors: Arnold B. M. , Kuttner M. , Willis D. M. , Hitchman A. J. W. , Harrison J. E. , Murray T. M.
Published: April 2011

Using a specific radioimmunoassay for porcine intestinal calcium-binding protein (CaBP), we have measured the concentration of CaBP in the various tissues and organs of normal pigs. Intestinal CaBP was present in highest concentration in the upper small intestine, with lower concentrations in the distal small intestine. Intestinal CaBP was also found, in lower concentrations, in kidney, liver, thyroid, pancreas, and blood. In all other tissues, including parathyroid, bone, skeletal muscle, and brain, CaBP immunoreactivity was undetectable or less than in blood. The elution profile of calcium-binding activity and immunoreactivity from gel filtration analysis of kidney and parathyroid extracts suggest that the calcium-binding protein in the parathyroid gland, and the major calcium-binding protein(s) in the kidney, are chemically and immunochemically different from intestinal CaBP.
Pulmonary Edema and Ascorbic Acid Loss
Authors: Willis R. J. , Kratzing C. C.
Published: April 2011

Loss of ascorbic acid from lung and pulmonary edema were produced in mice by intravenous injection of either adrenaline or noradrenaline (5 μmol/kg). While adrenalectomy performed before noradrenaline administration reduced the degree of pulmonary edema, a prior dose of hexamethonium accentuated this effect. Given alone, hexamethonium caused both loss of ascorbic acid and pulmonary edema. The results show that although endogenous catecholamines can potentiate the pulmonary edema produced by either adrenaline or noradrenaline, they play no specific role in the ascorbic acid loss. The evidence suggests that lung ascorbic acid levels are decreased following the development of pulmonary edema, irrespective of how it was caused.
Ionic Determinants of Spontaneous Activity in Clusters of Cultured Cardiac Cells from Newborn Rats
Authors: Schanne O. F. , Rivard C. , Doyon G.
Published: April 2011

The spontaneous activity of cell clusters derived from ventricle cells of newborn rats was studied using a recording television microscope. The influence of varying concentrations of sodium, potassium, calcium, tetrodotoxin (TTX), and that of 2 mM MnCl2 was tested. The spontaneous activity of the cell clusters persisted in TTX but it was abolished by Mn. The beating rate increased when [Ca]0 and [Na]0 were changed from 0.3 mM to 3.0 mM and from 30 mM to 75 mM; it decreased with a change of [Na]0 from 75 mM to 142 mM. It is concluded that electrogenesis in these cells is determined by a slow inward current and that these cell clusters are comparable in their behavior to very young embryonic rat heart cells or cells of the rabbit sinoauricular node.
A specific sugar transport mechanism in smooth muscle and its regulation
Authors: Bihler I. , Sawh P. C. , Elbrink J.
Published: April 2011

The membrane transport of 3-O-methyl-D-glucose was studied in vitro in a smooth muscle, the detrusor of rat urinary bladder. Transport occurred by facilitated diffusion and showed the same chemical specificity and sensitivity to specific inhibitors as skeletal and cardiac muscle but its insulin sensitivity was smaller. Transport was increased by agents inhibiting the Na+ pump and was decreased by agents which increased Na+ and K+ gradients by apparently stimulating the Na+ pump. In accord with a rate limiting role of transport in glucose utilization, similar stimulating and inhibitory effects were seen when CO2 production from [14C]glucose was measured.
Behavioral studies on the enantiomers of butaclamol demonstrating absolute optical specificity for neuroleptic activity
Authors: Voith Katherine , Cummings John R.
Published: April 2011

Butaclamol is a member of a new chemical class for which antipsychotic activity in humans has been demonstrated. Butaclamol, a racemate, has been resolved into its optical isomers and a separation of activities was found to occur between the (+) and (−) enantiomers. The present experiments show that at doses ranging from 0.1 to 0.3 mg/kg the (+) enantiomer abolished amphetamine-induced (a) stereotyped behavior and (b) rotational behavior in rats with unilateral lesions in the substantia nigra. It also inhibited the lever-pressing response in the continuous (Sidman) avoidance procedure, blocked discriminated avoidance behavior, and decreased ambulation and rearing in the open field. In contrast, the (−) enantiomer was devoid of behavioral activity at 100–500 times larger doses.At considerably higher doses (+)-butaclamol antagonized epinephrine-induced mortality. Again, the (−)-butaclamol was devoid of this activity as well. The significance of absolute optical specificity manifested by a neuroleptic drug is discussed in the light of dopaminergic and adrenergic mechanisms.
Nonparticipation of adrenergic mechanism in potassium-induced relaxation of taenia from guinea pig caecum
Authors: Kurahashi Kazuyoshi , Fujiwara Motohatsu
Published: April 2011

In the isolated taenia caeci of guinea pigs excess potassium (10–30 mM) induced a phasic relaxation followed by a contraction. This phasic relaxation was unaffected by treatment with hexamethonium, phentolamine, propranolol and bretylium. However, relaxation induced by perivascular nerve stimulation was inhibited by all these agents but not by hexamethonium. Tetrodotoxin inhibited both forms of relaxation. Potassium-induced relaxation was not accompanied by [3H]noradrenaline release. Perivascular nerve stimulation caused release of [3H]-noradrenaline and this was blocked by bretylium. Treatment with ouabain or replacement of NaCl by LiCl, but not treatment by cold storage, inhibited the potassium-induced relaxation. These results suggest that the potassium-induced relaxation of taenia caeci was due to electrogenic sodium pumping and was independent of the adrenergic innervation of the tissue.
Pituitary response to auditory stress: effect of treatment with α-methyl-p-tyrosine. Usefulness of a factorial mixed design for statistical analysis
Authors: Collu R. , Jéquier J.-C.
Published: April 2011

Eight adult male rats were chronically cannulated in the jugular vein and placed individually in a sound-attenuated cubicle. Four of the animals were also implanted with a permanent cannula in the right lateral ventricle of the brain. Each animal was submitted twice to auditory stress at a 24-h interval. Before each stress, the rats were pretreated with either saline or α-methyl-p-tyrosine (α-MT), the order of administration of the drug and its vehicle being alternated in the eight rats. The injections were made either intravenously or intraventricularly. Auditory stress significantly depressed plasma growth hormone (GH) levels irrespective of the type of pretreatment. Mean plasma GH levels were significantly lower after α-MT pretreatment. α-MT pretreated animals had higher mean plasma corticosterone (B) levels which remained unchanged during stress. Plasma follicle stimulating hormone (FSH) levels were not modified by stress nor by α-MT pretreatment. The intraventricular administration of α-MT at a dose (20 mg/kg) which is ineffective by a systemic route produced the same effects on GH and B levels as the intravenous injection (250 mg/kg). These data seem to indicate that auditory stress exerts its inhibitory effect on GH secretion through a noncatecholaminergic pathway. They show, on the other hand, the existence of a central catecholaminergic tonus, stimulatory for GH and inhibitory for B.Statistical analysis was based on a factorial mixed design for repeated measurements after logarithmic transformation of the data. The purpose, advantages and limits of this procedure are presented and discussed.
The effects of eazymetic digestion on the elastic properties of Isolated human cereberal arteries
Authors: Damude Leslie C. , Cope David A. , Roach Margot R.
Published: April 2011

Measurement of volume, pressure, and length were made on eight segments of human cerebral arteries perfused with chymotrypsin (CT) (EC 3.4.21.1) solution (pH = 7.8) for no more than 19 h, and on nine arterial segments perfused with combined enzyme (CT, trypsin (EC 3.4.21.4), elastase (EC 3.4.21.11)) solutions (pH = 7.8) for no more than 4 h. Circumferential tension–strain (and absolute radius) curves were obtained through the Law of Laplace (tension = pressure × radius). Initial and final elastances (tension/strain) were calculated after 0, 0.5, 1.0, 2.0, and 4.0 h of perfusion under the combined enzyme category, and after 0, 0.5, 1.0, 2.0, 4.0, 6.0, and 19.0 h of perfusion with CT. The initial elastance showed a significant increase (0.02 < p < 0.05) after about 6 h of perfusion. Increases in the final elastance became significant only after prolonged periods of perfusion with CT. Histological studies using light and scanning electron microscopy confirmed the removal of the elastic lamina as well as portions of the medial region. Fragmentation of the internal elastic lamina did not appear to affect the distensibility of major cerebral arteries in the 50- to 80-year-old age group.
Effects of reserpine on water, cation, and norepinephrine contents of cardiovascular tissues of normotensive dogs
Authors: Komatsu Yukio , Constantopoulos George , Gutkowska Jolanta , Rojo-Ortega Jose-Manuel , Genest Jacques
Published: April 2011

Six adult male mongrel dogs were treated orally with reserpine (0.03 mg/kg) for 6 weeks, after which time the arterial tissue content of water, cations (sodium, potassium, magnesium, and calcium), and norepinephrine was determined and compared with those of six untreated dogs. Reserpine administration resulted in sustained decreases in the mean arterial blood pressure and heart rate, and the arterial tissues of the treated dogs contained less potassium, calcium, and magnesium, the last-named being affected most, but the sodium remained the same. Arterial norepinephrine content was significantly decreased. There was a slight but significant increase in plasma magnesium, without any noticeable changes in other plasma cations. The reduction in the arterial magnesium by reserpine may help to regulate vascular tone and (or) vascular reactivity.
Myocardial lesions in rats fed rapeseed oil. II. Effects of castration
Authors: Hulan H. W. , Kramer J. K. G. , Corner A. H. , Thompson B.
Published: April 2011

The effects of castration on the incidence of myocardial lesions in rats were investigated in an experiment which included two factors: sex (entire males, castrated males, entire females and castrated (ovariohysterectomized) females) and diets (5% corn oil, 20% corn oil, and 20% Brassica napus var. Zephyr rapeseed oil). For 16 weeks, each of the 12 groups of 30 Sprague–Dawley rats, housed 2 per cage, were fed ad libitum the test oils incorporated in a semisynthetic diet. At each weighing, the mean body weights for each diet were highest in entire males followed by castrated males, castrated females, and entire females with all differences significant (P < 0.05). The results indicated that castration did not influence cardiac fatty acid composition. The incidence of myocardial lesions in entire and castrated females and in castrated males was similar while significantly more entire males developed lesions (P < 0.001). Rats fed a diet containing 20% Zephyr rapeseed oil showed a significantly (P < 0.001) higher incidence of heart lesions than did rats fed diets containing 5% or 20% corn oil. Similarly, significantly (P < 0.05) more rats fed the 20% corn oil diet had lesions than rats fed the 5% corn oil diet. The involvement of androgens in the formation of myocardial lesions is suggested, since castration significantly lowered the incidence in males but not in females.
Effect of 6-hydroxydopamine and α-methyltyrosine on brown adipose tissue of infant rats
Authors: Skala Josef P. , Hahn Peter
Published: April 2011

A single-dose administration of 6-hydroxydopamine (50 mg/kg body weight, sc) to infant rats resulted in an enlargement, higher fresh weight, markedly elevated lipid content, and higher total protein content of their interscapular and cervical brown adipose tissue. The protein kinase (EC 2.7.1.37) activation ratio in the tissue was decreased as was the phosphoenolpyruvate carboxykinase (EC 4.1.1.32) activity. Fatty acid synthetase, on the other hand, showed an increased activity. These changes commenced as soon as 24 h after the administration of the drug, were fully developed 2–4 days later, and persisted for at least 14 days. The results are in line with the assumption that 6-hydroxydopamine administration causes chemical sympathectomy of brown adipose tissue. This is further supported by the fact that treatment with α-methyltyrosine, which is known to competitively inhibit norepinephrine synthesis, results in similar changes in brown fat of infant rats. Hence it seems that 6-hydroxydopamine administration offers a simple and inexpensive experimental model for studies of the role of the norepinephrine-mediated sympathetic nervous system in brown adipose tissue function and development.
Goitres in rats fed polychlorinated biphenyls
Authors: Bastomsky C. H.
Published: April 2011

Rats fed a polychlorinated biphenyl (PCB) mixture in a high- or low-iodine diet (HID or LID, respectively) for 15 days had thyroid enlargement, low serum thyroxine (T4), and high serum thyrotropin concentrations. Although binding of thyroid hormones to serum proteins was reduced in PCB-fed animals, the free T4 index (reflecting free T4 in serum) was less in these rats. Both serum triiodothyronine (T3) and the free T3 index were elevated in rats fed PCB in HID. LID-maintained rats had elevated serum T3 concentrations but the free T3 index was similar to that in HID-fed rats, owing to enhanced binding of thyroid hormone to serum proteins. Addition of PCB to LID reduced serum T3 levels but did not alter the free T3 index because binding was less. In rats fed HID containing PCB, thyroid 131I uptake was increased.