bluuebunny/crossref_metadata_2025_split huggingface dataset:
Intrarenal Distribution of Blood Flow and Glomerular Filtration during Chronic Unilateral Ureteral Obstruction
Authors: Clausen G. , Hope A. 
Published: December 2008

AbstractPaired hydronephrotic (HN) and hypertrophic (HT) rat kidneys were studied after 6 days with complete unilateral ureteral obstruction without exposing the kidneys. Total HN renal blood flow (RBF), estimated by total microsphere (MS) uptake and from local125I‐antipyrine (Ap) uptake, averaged about 3/sec (n=147) for the extensor digitorum communis muscle and 3.39±0.68 m/sec (n=142) for the femoral quadriceps muscle. 4 of control. HN kidney GFR was reduced to about 1/2 of control level as estimated from inulin clearance of HT kidney times the HN to HT ratio for mean single nephron filtration rate, determined by14C‐ferrocyanide. Whereas blood flow (Ap) was proportionately reduced in outer and inner cortex (OC and 1C), fractional flow to the outer medulla (OM) was doubled as compared to controls (p < 0.01). Filtration was well preserved in deep as compared to superficial glomeruli with a smaller deep nonfiltering fraction (p > 0.02). Thus the results oppose the current concept that HN is characterized by disproportionate circulatory damage to IC and OM with little or no filtration in deep nephrons. In HT kidneys average RBF (MS) and GFR rose by about 1/2. Whereas total blood flow (Ap) rose proportionately in OC and IC, it remained at control level in OM, indicating dissociation between the total RBF and GFR and the effective blood flow to the OM zone.
Differentiation of Vasoconstrictor Sensitivity Caused by Prostaglandin E in Peripheral Vascular Beds of the Rabbit
Authors: Wennmalm ÅKe 
Published: December 2008

AbstractThe increase in perfusion pressure in the rabbit ear, hindleg and mesentery caused by close intra‐arterial injection of noradrenaline (NA), and the contractile response to NA of the rabbit aortic strip were investigated with respect to their sensitivity to prostaglandin E1(PGE1) and to the prostaglandin synthesis inhibitor indomethacin. PGEj (100–200 ng) potentiated the increases in perfusion pressure caused by NA in the perfused hindleg and mesentery, and the contractile response to NA of the aortic strip by 25–80%, but inhibited the increase in perfusion pressure by NA in the perfused ear by 35–100%. Indomethacin (3–5 10‐5M) significantly decreased the pressor responses to NA in the hindleg (by 45%) and mesentery (by 55%). This inhibitory effect by indomethacin was completely reversed by PGE1. The responses to NA in the aortic strip and the perfused ear were unaffected by indomethacin. It is concluded that the process of vasoconstriction in the vascular beds of the rabbit displays qualitative differences concerning its sensitivity to added PGEj. Furthermore, the decreased pressor responses to NA observed in some of the rabbit vascular beds after indomethacin indicate that the sensitivity to NA in these tissues in fact is increased by endogenous prostaglandin‐like substances (PLS). The current results thus suggest that endogenous PLS may regulate, at a local level, the vasoconstrictor sensitivity in the rabbit systemic resistance vessels.
The Compliance Curve for the Flow Limiting Segments of the Airway
Authors: Pedersen Ole Find , Nielsen Tage Mors 
Published: December 2008

AbstractMaximum effort flow‐static recoil curves were obtained in 5 healthy subjects breathing air, He/O2, and SF6/O2 mixtures. In 4 of them maximum effort flows corresponded to really maximal flows and their curves were transformed into compliance curves for the flow limiting segments of the airway and analyzed from the point of view of a previously presented lung model (Pedersen and Nielsen 1976). The results showed, that viscosity dependent pressure losses from the alveoli to the flow limiting segments were minimal for air and SF6/O2, but not for He/O2. When viscosity dependent pressure losses could be neglected, then expiration of gases of different densities gave almost identical compliance curves for the flow limiting segments. This supported the applicability of the model. The calculated compliance curves for the flow limiting segments were compared with data from the literature, and the findings indicated that flow limitation during expirations with just maximal flows throughout began in the extrapulmonary airways and moved upstream during the expiration.
Effects of Prostaglandins on the Isolated Human Bladder and Urethra
Authors: Andersson K.‐E. , Ek A. , Persson C. G. A. 
Published: December 2008

AbstractThe effects of prostaglandins F2α (PGF2α), E2 (PGE1) and E2 (PGE2) on the human lower urinary tract were studied in vitro in preparations obtained from patients undergoing total cystourethrectomy because of bladder malignancy. Tissue specimens were taken from different parts of the urethra, the urethrovesical junction, and the bladder. From these specimens, smooth muscle preparations were dissected and mounted in organ baths, that were filled with Krebs solution (37°C) and bubbled with carbogen. Isometric tension was recorded. Preparations from the bladder and all parts of the urethra were contracted by PGF2α. This effect was not affected by tetrodotoxin, phenoxybenzamine, or atropine; isoprenaline relaxed the PGF2α induced contractions. PGE1 and PGE2 both contracted strips from the bladder. However, urethral preparations contracted by PGF2α or noradrenaline were relaxed by these agents. This relaxing effect was at least as pronounced as that produced by isoprenaline; it was not affected by propranolol.
Brain Energy Metabolism in Angiotensin‐Induced Acute Hypertension in Rats
Authors: Johansson Barbro B. , Siesjö Bo K. 
Published: December 2008

AbstractIn order to study if rapid elevation of blood pressure is associated with cerebral ischemia, anesthetized (70% N2O) and artificially ventilated rats were subjected to angiolensin‐induced hypertension. After a 5 min hypertensive period, cerebral cortex tissue was frozen in situ for subsequent measurements of labile glycolytic metabolites, ammonia, and organic phosphates. The degree of hypertension induced, which gave evidence of blood–brain barrier damage in 7 of 8 rats, did not affect the tissue concentrations of labile metabolites. It is concluded that ischemia does not contribute to the barrier damage, nor is it likely to be the cause of the clinical symptoms that may occur in conscious rats in the same experimental model.
The Fate of Intravenously Administered Radioactive Cholesterol Dispersion in the Rat
Authors: Viikari J. , Saarni H. , Ruuskanen O. , Nikkari T. 
Published: December 2008

AbstractThe present work was aimed at studying the first stages of disappearance of particulate cholesterol from the circulation. The distribution of radioactivity in blood, liver, spleen, lungs and kidneys was determined at different time intervals after i.v. injections of aqueous‐ethanolic dispersions of radioactive cholesterol to rats. More than 95% of the dose disappeared from the circulation in 10 min. From 71 to 93% of the dose was found in the liver 5 min‐2 h after the injection. According to autoradiography, most of the particulate cholesterol was immediately taken up by the liver parenchymal cells. There were only few grains over the Kupffer cells. 2 min to 6 h after the injection the highest specific radioactivity was in the free cholesterol fraction of the liver. The specific activity of liver esterified cholesterol was 54 % of that of the free cholesterol at 1 h. They both declined gradually and reached the same level in 1–2 days. There was a gradual rise of the specific activities of plasma free and esterified cholesterol starting 30 min after the injection. Both reached a maximum in 6–16 h, when the curve of plasma esterified cholesterol intersected that of liver esterified cholesterol. The radioactivity reappearing in plasma was associated with lipoproteins and red cells; the cholesterol of the high density lipoproteins had the highest specific activity. The results indicate that particulate cholesterol is taken up chiefly by the parenchymal cells of the liver and is subsequently incorporated into the plasma lipoproteins, most rapidly into the high density lipoproteins. A large fraction of plasma esterified cholesterol originates in the liver.
Small Airway Constriction and Closure after Induced Intravascular Platelet Aggregation
Authors: Vaage Jarle , Hauge Anton 
Published: December 2008

AbstractThe aim of this study was to investigate the function of the peripheral airways after intravascular platelet aggregation induced by i.v. infusions of collagen in open chest anesthetized cats, ventilated with constant tidal volume. Lung compliance was examined under static conditions (stat CL) and under dynamic conditions (dyn CL) at ventilation frequencies of 5, 24 and 50/min. In the control situation dyn CL 24 was approximately 90 % of stat CL. Collagen infusions resulted in a pronounced frequency‐dependence of lung compliance. When dyn CL 24 had decreased by approximately 40 % a reduction in stat CL could also be detected. When dyn CL 24 decreased even more a concurrent reduction in stat CL was evident. These findings indicate that the initial event after induced intravascular platelet aggregation is small airway constriction. With more pronounced changes airway closure and reduction in lung volume occurs. We suggest that these functional changes in peripheral airways result in the impaired gas exchange known to occur after intravascular platelet aggregation.
Inhibition of Gastric and Intestinal Motor Activity in Dogs by (Gln4) Neurotensin
Authors: Andersson S. , Rosell S. , Hjelmquist U. , Chang D. , Folkers K. 
Published: December 2008

AbstractThe action of (Gln4)‐neurotensin was studied on the spontaneous motor activity in isolated canine fundic, antral and intestinal pouches. All pouches had been prepared more than 6 months prior to the experiments. Spontaneous motor activity was recorded for at least 1 h before the (Gln4)‐neurotensin was infused i.v. for 30 min in doses ranging between 6.3 and 100 ng × kg‐1× min‐1. In the vagally denervated fundic pouches (Gln4)‐neurotensin inhibted motor activity in doses above 25 ng × kg‐1× min‐1. The vagally innervated antral pouches were more sentitive than the vagally denervated fundic pouches to the action of (Gln4)‐neurotensin. Thus motor inhibition was induced by doses as low as 6.3 ng × kg‐1× min‐1. The effect of (Gln4)‐neurotensin on motor activity in intestinal pouches was inconsistent. Inhibition was seen in 1 out of 7 expts. The present results show that the gastric motor activity is the most sensitive function to (Gln4)‐neurotensin so far studied.
Blood Volume and Extravascular Water Content in the Rat Lung during Acute Alveolar Hypoxia
Authors: Aarseth P. , Karlsen J. 
Published: December 2008

AbstractValues for pulmonary blood volume and extravascular lung water (estimated as wet weight of lung tissue) were arrived at in intact, anesthetized rats by labelling of blood constituents with isotopes and rapidly freezing the whole animals in liquid nitrogen. On ventilating the animals with 10% O2 in N2/N2O. a reduction in lung blood content could be demonstrated. The degree of reduction depended on the type of anesthesia and ventilation used. In some animals the volume reduction was so marked that both arterial, venous and capillary blood compartments have most probably been involved. The water content of the lung tissue was also rapidly and markedly reduced during hypoxia. Increased plasma osmolarity in mixed venous blood could partly be responsible for this tissue water reduction.
Effect of Teasing and Sham Feeding on Plasma Glucagon Concentration in Dogs
Authors: Nilsson Göran , Uvnäs‐Wallensten Kerstin 
Published: December 2008

AbstractPlasma glucagon concentration was determined by radioimmunoassay during fasting and following teasing and sham feeding. Teasing and sham feeding for 1–10 min raised the plasma glucagon concentration which then within a short period of time returned to the basal level. Atropinization (0.2 mg/kg) almost abolished the glucagon response to 10 min of sham feeding. Glucose concentration was slightly elevated in response to 10 min of sham feeding. The results show that physiological stimulation that is induced by the smell. sight and taste of food releases glucagon in the dog. The release is mediated by a cholinergic mechanism.
Pressure‐Independent Inhibition of Sympathetic Activity by Noradrenaline: Role of Baroreceptor C Fibres*
Authors: Akre Stein , Aars Harald 
Published: December 2008

AbstractThe effect of i.v. infusion of noradrenaline on activity in the renal sympathetic nerve was studied in rabbits anesthetized with chloralose and urethane. Noradrenaline (3–8 μg/kg·min) initially increased mean arterial pressure 20–40 mmHg and consequently reduced renal nerve activity. However, studies over a wide range of pressures—obtained by changing the blood volume, revealed that noradrenaline after a few minutes had induced a pressure‐independent reduction of sympathetic discharge. The effect disappeared with baroreceptor denervation. An unchanged relationship between arterial pressure and integrated activity in the whole left aortic nerve (which is largely a measure of activity in A fibres) suggested that the sympathetic depression was due to excitation of aortic nerve C fibres. This conclusion was supported by studies of sympathetic responses to selective stimulation of aortic nerve A and C fibres at equal pressures before and during infusion of noradrenaline. Compared to the reflex activity from A fibres, C fibre stimulation was invariably less effective in suppressing renal nerve activity during the infusion. Our studies indicate that noradrenaline may effect a negative feedback control of sympathetic discharge through activation of baroreceptor C fibres.
Comparative Study of Some Isolated Mammalian Smooth Muscle Effectors of Penile Erection
Authors: Klinge Erik , Sjöstrand Nils O. 
Published: December 2008

AbstractSpontaneous rhythmic activity, responses to drugs and effects of field stimulation of nerves of the retractor penis (rp) and/or corpus cavernosum urethrae (ceu) of macaque, rabbit, guinea‐pig, rat, dog, cat, horse, boar, elk, bull, ram and goat, as well as of the penile artery (pa) of bull were studied. A basic property of all these muscles was automaticity. Their responses to 5‐hydroxytryptamine, histamine, adenosine triphosphate, prostaglandins E1, E2 and F2α, oxytocin, vasopressin, substance P, bradykinin and angiotensin exhibited considerable species variations. Their excitatory innervation seems to be adrenergic. They also have an inhibitory innervation. In spite of comprehensive pharmacological analysis the inhibitory mediator remains obscure. The frequency‐response relationship to inhibitory nerve stimulation was characterized by a rapidly achieved maximum at low frequencies, indicating high efficiency of the neuroeffector unit.
The Importance of the Intestinal Countercurrent Exchanger for 85Kr Absorption from the Feline Gut
Authors: Jodal Mats , Svanvik Joar , Lundgren Ove 
Published: December 2008

AbstractThe rate of 85Kr absorption from the feline gut was studied at varying intestinal blood flows induced by i.a. infusions of a vasodilator drug or by lowering arterial inflow pressure. The effects on rate of absorption of distending the intestine by increasing intraluminal pressure from 0–1 to 5–7 cm H2O as well as of augmenting the rate of luminal perfusion of the 85Kr solution were also investigated. Distending the small bowel increased rate of 85Kr absorption at all levels of intestinal blood flow except at the very low and the very high blood flow rates. Decreasing blood flow by lowering of arterial perfusion pressure decreased the rate of absorption from the distended gut while it had no effect in the collapsed small intestine. Increasing the rate of luminal perfusion enhanced the rate of 85Kr absorption at all blood flow levels except at the lowest ones. The results are discussed with regard to villous hemodynamics, intestinal countercurrent exchange and intraluminal concentration gradients in the lumen. It is concluded that the countercurrent exchanger represents, under physiological conditions, the major limiting factor for the absorption of lipophilic solutes such as 85Kr.
Absence of Restricted Diffusion in Adipose Tissue Capillaries
Authors: Paaske William P. 
Published: December 2008

AbstractCapillary permeability in adipose tissue for57Co‐cyanocobalamin (57Co‐B12) was determined by the single injection, external registration method. The capillary diffusion capacity, CDC, (the permeability‐surface area product, PS) was 1.1 ml/100 g·min at a capillary extraction of 0.21 and a plasma flow of 6.7 ml/100 g·min. Results were compared to51Cr‐EDTA data from a previous study with similar method and preparation. As CDC(51Cr‐EDTA)/CDC (57Co‐B 12) was 1.81 and as D(51Cr‐EDTA)/D(57Co‐B 12), the ratio between the free diffusion coefficients in water at 37°C, was 1.79, it is concluded that restricted diffusion does not occur in cutaneous tissue for57Co‐B 12 as compared to51Cr‐EDTA,i.e.,51Cr‐EDTA and57Co‐B 12 diffuse across the capillary membrane of adipose tissue at rates proportional to their respective free diffusion coefficients in water. The Pappenheimer equivalent pore radius estimate of 30 Å and the Karnovsky interendothelial 40 Å slit width are both defective in explaining the experimental data. The transendothelial channel system of fused vesicles (Simionescu, Simionescu and Palade 1975) is a possible structural equivalent for the present findings. The results support the hypothesis that capillaries of continuous type exhibit similar permeation characteristics regardless of the tissue in which they are located.
Effect of Carotid Sinus Stimulation on Cardiac Output and Peripheral Vascular Resistance during Changes in Blood Volume Distribution in Man
Authors: Bevegård Sture , Castenfors Jan , Lindblad Lars Erik 
Published: December 2008

AbstractIn ten healthy subjects (mean age 29.6 years) the hemodynamic response to carotid sinus stimulation (neck suction ‐ 40 mmHg) was studied under control conditions and during peripheral pooling of blood (lower body negative pressure). Heart rate, arterial and central venous pressure, cardiac output and forearm blood flow were measured. The time sequence of the heart rate response was studied separately in six healthy subjects. During control conditions, carotid sinus stimulation induced a significant decrease in arterial pressure and heart rate. The blood pressure decrease mainly reflected a reduction in cardiac output, total peripheral vascular resistance being essentially unchanged. However, in the skeletal muscle, represented by a forearm segment, vascular resistance decreased significantly. During lower body negative pressure (LBNP) the same stimulation of the carotid sinus induced a significantly greater fall in mean arterial pressure even though the reduction in cardiac output was slightly smaller on the average than in the control condition. The heart rate increased, probably secondary to a time dependent increase in heart rate elicited by the continuous LBNP stimulus. Total peripheral vascular resistance decreased significantly during LBNP, the reaction likewise differing significantly from that in the control condition. Thus the augmented blood pressure response was due to a more pronounced vasodilatation when the carotid sinus was stimulated during lower body negative pressure. The results indicate that the hemodynamic changes elicited by carotid sinus stimulation are modified by changes in the distribution of blood volume and in the tone of resistance vessels.
Adenosine in Rat Cerebral Cortex: Its Determination, Normal Values, and Correlation to AMP and Cyclic AMP during Shortlasting Ischemia
Authors: Nordström C.‐H. , Rehncrona S. , Siesjö B. K. , Westerberg Eva 
Published: December 2008

AbstractIt has recently been suggested that adenosine is a metabolic coupling factor responsible for an increased cerebral blood flow during hypoxia or increased functional activity. However, tissue adenosine concentrations have been reported to increase in situations previously shown to be unassociated with changes in tissue AMP concentrations. The present experiments were undertaken to assess cerebral cortex concentrations of adenosine under normal circumstances, and to relate changes in adenosine, AMP and cyclic AMP during shortlasting ischemia. Following freezing and extraction of tissue, adenosine was measured using high pressure liquid chromatography. In paralyzed and anaesthetized (70% N2O) rats, freezing of tissue through intact skull bone gave an adenosine concentration of 0.9 ± 0.1 μmol·kg‐1(mean±S.E.M). With freezing through the exposed dura the concentration was 3 times as high with a large scatter. When special precautions were taken to avoid tissue trauma during craniotomy, the adenosine concentration was 1.1 ± 0.1 μmol·kg‐1. It is concluded that previously reported values are erroneously high. During the first 60 s of total ischemia there was a linear correlation between increase in AMP and in adenosine concentration (as well as between adenosine and cyclic AMP concentrations). It is concluded that increases in tissue adenosine concentration only occur if AMP accumulates. However, since (relative) changes in adenosine concentrations are at least twice those of AMP, analyses of adenosine may provide sensitive measures of a change in phosphorylation state.
Dependence on External Calcium for the Noradrenaline Contractility of the Resistance Vessels in Spontaneously Hypertensive and Renal Hypertensive Rats, as Compared with Normotensive Controls
Authors: Folkow Björn , Hallbäck Margareta , Jones John V. , Sutter Morley 
Published: December 2008

AbstractIsolated hindquarters of rats were perfused at constant flow with a plasma substitute so that pressor responses to various concentrations of noradrenaline (NA) could be measured in consecutive sections of the vascular bed with normal (>1.5 mM) or low (0.2 mM) Ca2+in the perfusate. The animals used were 6‐week‐old spontaneously hypertensive rats of the Okamoto strain (SHRY), normotensive controls of the same age (NCRY); 6–7‐month‐old SHR (SHRA) and NCR (NCRA); and rats made hypertensive by clipping of one renal artery (RHR) plus matched normotensive controls (NCRB). Concentration‐response curves to NA showed that constrictor responses to NA become more dependent on external calcium as one proceeds peripherally in the vascular system in both SHRA and NCRA, with responses in proximal vessels being least and small pre‐and postcapillary vessels being most dependent in both cases. In low calcium SHRA retained their responses better than NCRA, whereas RHR retained their responses to NA poorer than did NCRB. No significant differences in responses in low calcium were observed in SHRT compared to NCRY though a trend in the same direction as in SHRA could be traced. It is concluded that there is no evidence that altered handling of calcium initiates vascular hyperreactivity in SHR, but that the handling of vascular calcium in SHR differs from RHR and both differ from NCR.