bluuebunny/crossref_metadata_2025 huggingface dataset:
Seventy years of the Bainbridge reflex
Authors: HAKUMÄKI M. O. K.
Published: December 2008

The discovery of the Bainbridge reflex 70 years ago, of a tachycardic response to a rise in central venous pressure, stimulated a lot of interest in this and other cardiovascular reflexes. The mechanoreceptors that elicit the reflex are located at the junction of the right atrium and caval veins or at the junctions of the pulmonary veins and the left atrium. The Bainbridge reflex is controversial, however, because its existence cannot always be demonstrated. Intravenous infusions, which usually elicit a reflex tachycardia, sometimes cause a bradycardic response. This paper reviews the history of the studies associated with the reflex. Results are reported, which demonstrate that the chronotropic response to i.v. infusions depends upon the resulting change in aortic diameter; bradycardia is evoked by infusions leading to a rise in aortic baroreceptor activity through increases in aortic diameter, volume or pressure; tachycardia follows whenever the infusion fails to trigger the baroreflex. The importance of the Bainbridge reflex as a counterbalance to the baroreceptor reflex is discussed.
Influence of perfusate oncotic pressure on the transcapillary clearance of albumin in maximally vasodilated rat skeletal muscle
Authors: HARALDSSON B. , RIPPE B.
Published: December 2008

An external detection technique was developed for repetitive and reliable measurements of clearance (Cl) of 99m Tc‐albumin during alterations of serum colloid osmotic pressure (πp). Isolated, maximally vasodilated rat hindquarters were perfused with serum of two πPs (20 mmHg and 45 mmHg) at four or five different filtration rates (Jv) for each πp in each animal. The recorded accumulation rates of 99m Tc‐albumin (AR) were converted into dimensions of albumin clearance, setting the isogravimetric C1 at normal vascular pressures (πp= 20 mmHg) at 0.0246 ± 0.0012 ml min‐1 per 100 g, which was obtained in defined muscle samples in 11 seperate experiments. Serum perfusion with higher colloid osmotic pressure (45 mmHg) shifted the albumin clearance values upwards, without affecting the slope of the CI vs. Jv relationship. Thus, the reflection coefficient (a) for albumin did not seem to be affected by the changes in πp, while the isogravimetric albumin clearance was increased to roughly 0.058 ml min‐1 per 100 g. Explicit two‐pore equations were found to describe the experimental data fairly well, yielding an average s̀ for albumin of 0.92 and a minor contribution of diffusion to overall transport even at low JVs. Moreover, a coupling of macromolecular clearance to πp may serve to minimize alterations in plasma protein concentration.
Effects of adrenoceptor antagonists on vagally induced gastric and duodenal HCO3‐secretions in the cat
Authors: FANDRIKS L. , JÖNSON C.
Published: December 2008

Experiments were performed on chloralosed cats with ligated adrenal glands. The cervical vagi were cut and arranged for electric stimulation. The gastric lumen was continuously perfused, and the secretions of H+and HCO3‐were calculated from pH/Pco2measurements in the perfusate. Gastric motility was recorded as changes in hydrostatic pressure within the perfusion system. Mucosal HCO3‐secretion into a duodenal segment, distal to the papilla of Vater and Brunners gland area, was titratedin situby a pH‐stat equipment. Animals pretreated with various adrenoceptor blockers or splanchnicotomy were compared with control animals with intact sympatho‐adrenergic system. Basal gastric motor activity, H+and HCO3‐secretions, as well as duodenal HCO3‐secretion were not influenced by prazosin, propranolol or splanchnicotomy. Yohimbine increased significantly basal gastric HCO3‐secretion, but did not influence basal gastric motor activity, H+secretion or duodenal HCO3‐secretion. Vagal stimulation in yohimbine‐treated or splanchnicotomized animals induced significantly larger gastric contractions, HCO3‐secretory and duodenal HCO3‐secretory responses than in the controls, whereas these responses to vagal stimulation were small in prazosine‐ or propranolol‐treated animals. Vagally induced gastric H+secretory responses were significantly larger in propranolol‐treated animals than in controls, whereas prazosin‐treated, yohimbine‐treated or splanchnicotomized animals in this regard did not differ from the controls. The results suggest the existence of a sympathetic, probably alpha‐2–adrenergic, inhibition of vagally induced gastric contractions as well as of the gastric and duodenal HCO3‐secretions.
Haemoglobin O2 binding in newborn and adult rabbits
Authors: HOLTER P. H. , KIERULF P. , REFSUM H. E.
Published: December 2008

The relationship between haemoglobin O2 saturation and 2,3–diphosphoglycerate concentration (q‐DPG) in haemoglobin solutions equilibrated with 3.7% O2‐5.7% CO2 were identical in newborn and adult rabbits over a wide range of 2,3–DPG (0.5–40.0 μmol g‐1 Hb), and independent of the haemoglobin concentration (1–10 g dl‐1). Also, the resistance of the haemoglobin to alkali denaturation and the spectrophotometric absorption spectra of carboxy and oxyhaemoglobin between 500 nm and 650 nm, as well as the isoelectric focusing pattern of the haemoglobin after early and late stabilization with CO, were the same in newborn and adult animals. Both demonstrated one dominant band, focusing at pH 7.17, and one less conspicuous at pH 7.40. The erythrocyte pH was higher in the newborn than in the adult animals. Isoelectric focusing of erythrocyte pyruvate kinase demonstrated two isoenzyme bands in the newborn animals, one dominant fraction at pH 5.85 and one minor fraction at pH 7.97, whereas only the pH 7.97 band was observed in the adult. It is concluded that the physical properties of the haemoglobin molecule itself are the same in newborn and adult rabbits, and that the postnatal decrease in haemoglobin O, affinity is solely due to changes in the erythrocyte metabolism, leading to a marked rise in 2,3–DPG and a minor decline in erythrocyte pH. The rise in 2,3–J‐DPG is caused by decrease of pyruvate kinase, probably due to proteolytic inactivation of the enzyme.
Effects of atrial natriuretic peptide (ANP) during converting enzyme inhibition
Authors: HANSELL P. , ULFENDAHL H. R.
Published: December 2008

Effects of atrial natriuretic peptide (ANP) during converting enzyme inhibition.Acta Physiol Scand130, 393–399. Received 1 December 1986, accepted 10 February 1987. ISSN 0001–6772. Department of Physiology & Medical Biophysics, Biomedical Centre, University of Uppsala, Sweden.

Studies were performed on anaesthetized adult Münich‐Wistar rats to investigate the role of angiotensin 11 in the natriuretic response to synthetic atrial natriuretic peptide (ANP, 28 amino acids). For this purpose the whole kidney glomerular filtration rate (GFR) and urinary excretion of electrolytes were measured in groups of animals pretreated with the converting enzyme inhibitor captopril (3 mg h‐1kg‐1body wt) or vehicle and then given a continuous intravenous infusion of ANP at 10 μg h‐1kg‐1body wt. In the vehicle‐pretreated animals, 45 min of ANP infusion did not change GFR (control value 1.17 ± 0.11, experimental value 1.17 ± 0.06 ml min‐1g‐1kidney wt). Sodium excretion (UNaV) increased more than three‐fold from 0.036 ± 0.010 to 0.134 ± 0.058 pmol min‐1g‐1kidney wt (p0.05) and potassium excretion (UKV) increased from 0.481 ± 0.055 to 0.946 ± 0.068 μmol min‐1g‐1kidney wt (P0.05). Urine osmolality (UOsm) remained unchanged, while the blood pressure (BP) decreased by 15%. In animals pretreated with captopril, ANP infusion led to a decrease in GFR from 1.27 ± 0.11 to 1.05 ± 0.09 ml min‐1g‐1kidney wt (P0.05). Despite this effect,UNaVincreased more than two‐fold from 0.076 ± 0.020 to 0.193 ± 0.087 μmol min‐1g‐1kidney wt (P0.05). TheUKVwas not statistically significantly elevated (change from 0.623 ± 0.156 to 0.859 ± 0.146 μmol min‐1g‐1kidney wt) andUOsmremained unaltered, while BP decreased by 15% (P0.05). The captopril‐pretreated animals had a higher UNaVvalue during the control period than vehicle‐pretreated ones, but there was no statistical difference in this variable between the groups after ANP infusion. The captopril treatment decreased BP by 6%. It is concluded that converting enzyme inhibition induced by captopril does not interfere with either the natriuretic or with the hypotensive response to ANP, which suggests that angiotensin II does not participate in the generation of the acute effects of ANP. Atrial natriuretic peptide increases sodium excretion predominantly by affecting tubular transport processes, and not by increasing GFR.
Release of vasoactive intestinal polypeptide anally of a local distension of the feline small intestine
Authors: SJÖQVIST A. , FAHRENKRUG J.
Published: December 2008

Release of vasoactive intestinal polypeptide anally of a local distension of the feline small intestine. Acta Physiol Scand 130, 433–438. Received 12 February 1987, accepted 27 February 1987. ISSN 0001–6772. Department of Physiology, University of Göteborg, Sweden, and Department of Clinical Chemistry, Bispebjerg Hospital, Copenhagen, Denmark.

The peristaltic reflex is elicited by a local distension of the intestine and consists of an ascending contraction and a descending inhibition of the smooth muscle layer. The transmitter mediating the inhibition of the smooth muscle cells is not known but vasoactive intestinal polypeptide (VIP) has, among others, been proposed to mediate the descending inhibition of a distension. An in vivo preparation of a segment of the feline intestine was designed to allow collection of the venous effluent and determination of the VIP release orally and anally of a distension. The release of VIP rose significantly more on the anal side of the intestinal distension, and so did the blood flow. Division of the myenteric plexus prevented the asymmetry of the VIP release to a large extent. These effects of distension on the release of VIP are consistent with the hypothesis that VIP mediates the descending inhibition of the peristaltic reflex.
Oxygen dependency of preovulatory follicles from pregnant mare serum gonadotropin‐treated immature rats
Authors: SELSTAM G. , GÅFVELS M.
Published: December 2008

Oxygen dependency of preovulatory follicles from pregnant mare serum gonadotropin‐treated immature rats. Acta Physiol Scand 130, 483–489. Received 8 January 1987, accepted 27 February 1987. ISSN 0001–6772. Department of Physiology, University of Umei, Sweden.

The present study was initiated to test to what extent preovulatory follicles are dependent on oxygen supply for maintaining their response to luteinizing hormone (LH). Female rats of the Sprague‐Dawley strain were injected with 6 IU of pregnant mare serum gonadotropin (PMSG) on their 26th day of life. For in vitro experiments rats were killed 48–52 h after PMSG injection.

Preovulatory follicles were dissected free, pre‐incubated for 30 min and then incubated for J h without or with luteinizing hormone (LH, I μg ml‐1 medium) under different oxygen tensions in the gas phase (100,13,6 and o kPa). After incubation the accumulation of progesterone, cyclic‐3′, 5′‐adenosine monophosphate (cyclic AMP) and lactic acid were measured in the incubation media. Follicular adenosine‐5′‐triphosphate (ATP) content was measured in vivo (48–60 h after PMSG injection) immediately after isolation as well as after the incubation. Follicles isolated in vivo, during and after the ovulatory endogenous gonadotropin surge showed a depression in follicular ATP levels compared with levels before, suggesting that gonadotropins stimulate the follicle on the expense of ATP levels during the course of the preovulatory day. During a step‐wise decrease of oxygen tension in vitro the preovulatory follicle maintained its response to LH as measured by progesterone and cyclic AMP accumulation. The preovulatory follicle could apparently compensate by increasing glycolysis, as measured by an increase in lactic acid accumulation. Tissue ATP levels were during these conditions maintained. However, at a near‐total lack of oxygen (approximately o kPa) the progesterone and cyclic AMP response to LH was dramatically lowered as well as ATP levels. Thus, the preovulatory follicle can maintain progesterone production during hypoxia by at least partly compensating energy demand by increasing anaerobic glycolysis.
Changes in elemental composition of human muscle fibres following surgery and immobilization. An X‐ray microanalytical study
Authors: WROBLEWSKI R. , ARVIDSSON I. , ERIKSSON E. , JANSSON E.
Published: December 2008

Changes in elemental composition of human muscle fibres following surgery and immobilization. An X‐ray microanalytical study. Acta Physiol Scand 130, 491–494. Received 17 December 1986, accepted 16 February 1987. ISSN 0001–6772.

King Gustav V Research Institute, Section of Trauma, Department of Surgery, and Department of Clinical Physiology, Karolinska Hospital, Stockholm, Sweden.

X‐ray microanalysis of single muscle fibres visualized in the electron microscope has been applied to human muscle biopsies to quantify changes of intracellular elements after knee‐surgery with subsequent immobilization for 6 weeks. An increase of intracellular chlorine (Cl; P 0.001) and of sodium (Na; P 0.1) concentrations were found 1 and 6 weeks post‐surgery. Intracellular potassium (K), phosphorus and sulphur concentrations were not significantly changed. The increased Cl and Na concentrations may be an indication of a decreased activity of the ATPasedependent Na/K‐pump in the sarcolemma and/or of an increased sarcolemmal permeability for Na and Cl.
Motility in auditory sensory cells
Authors: ULFENDAHL M.
Published: December 2008

Motility in auditory sensory cells. Acta Physiol Scand 130, 521–527. Received 7 January 1987, accepted 27 February 1987. ISSN 0001–6772. Department of Physiology II, Karolinska Institute, Stockholm, Sweden.

Three different procedures were employed to induce contraction of isolated cochlear outer hair cells. When cells were permeabilized and exposed to calcium and ATP both a shortening of cell length (14%) and a decrease in cell diameter (12–16%) was observed indicating a longitudinal and a circumferential contraction. When intact cells were treated with positively charged ferritin a shortening of about 10% was observed together with an increase in cell diameter. Application of solutions containing high potassium concentrations gave similar but more rapid results as compared with positively charged ferritin. The observed responses of inner ear sensory cells together with their morphological and immunohistochemical characteristics further support the idea that the hearing organ acts as a motile system.
Source of calcium for contractions induced by depolarization and muscarinic receptor stimulation in rabbit urinary bladder
Authors: BATRA S. , SJÖGREN C. , ANDERSSON K.‐E. , FOVAEUS M.
Published: December 2008

Source of calcium for contractions induced by depolarization and muscarinic receptor stimulation in rabbit urinary bladder.Acta Physiol Scand130, 545–551. Received 4 December 1986, accepted 20 March 1987. ISSN 0001–6772. Departments of Obstetrics and Gynaecology and Clinical Pharmacology, University of Lund, and AB Leo Research Laboratories, Helsingborg, Sweden.

Omission of calcium or the inclusion of lanthanum in the bathing medium resulted in an almost complete inhibition of contractile responses induced by either K+depolarization or carbachol in strips of rabbit urinary bladder. D‐600 inhibited K+‐induced contractions significantly more than carbachol‐induced responses. The influx of45Ca into cells was stimulated both by K+depolarization and carbachol. Over a 2‐min period the increase in46Ca influx induced by high K+and carbachol was 98 and 65%, respectively. Both lanthanum and D‐600 blocked45Ca influx stimulated by either K+depolarization or carbachol. The inhibition of45Ca influx by these calcium‐channel blocking agents, particularly by D‐600, was dependent on the length of exposure. Application of carbachol during45Ca efflux in pre‐loaded muscle strips had no effect on the rate of45Ca efflux. These results indicate that the contractile responses of the urinary bladder to depolarization and to carbachol are highly dependent on an extracellular source of calcium.
The influence of cardiopulmonary receptors on long‐term blood pressure control and plasma renin activity in conscious dogs
Authors: PERSSON P. , EHMKE H. , KIRCHHEIM H. , SELLER H.
Published: December 2008

The influence of cardiopulmonary receptors on long‐term blood pressure control and plasma renin activity in conscious dogs. Acta Physiol Scand130, 553–561. Received 14 November 1986, accepted 6 March 1987. ISSN 0001–6772. I. Physiologisches Institut, Universität Heidelberg, Federal Republic of Germany.

The isolated and combined influence of cardiopulmonary and arterial baroreceptor denervation on long‐term blood pressure (MAP), heart rate (HR), plasma volume (PV) and plasma renin activity (PRA) was studied in 10 conscious, chronically instrumented foxhounds receiving a normal sodium diet. Cardiopulmonary denervation was achieved by surgically stripping both thoracic vagi. Near complete arterial baroreceptor denervation, leaving most cardiopulmonary fibres intact, was made by left vagal deafferen‐tiation which has been shown to eliminate most aortic baroreceptor afferents, and a carotid sinus denervation. Five groups were studied: (I) control (n = 9), (II) cardiopulmonary denervation (n= 5), (III) aortic baroreceptor denervation (n = 5), (IV) arterial baroreceptor denervation (n= 4) and (V) total denervation (n= 6). No changes in PV were observed. Only group V revealed significantly higher levels of MAP (119.5 ± 5.4 us. 100.1±1.6 mmHg; P 0.05), HR (118.1±4.4 us. 87.8 ± 3.7 beats min‐1; P 0.001) and PRA (3.0±0.8 us. 0.9 ± 0.2 ng A1 m‐1 h‐1; P 0.05). It is suggested that the isolated function of either cardiopulmonary or arterial baroreceptors is sufficient to maintain these variables at a normal level. Contrary to the results of other reports the cardiopulmonary receptors do not seem to regulate MAP at a level about which the arterial baroreceptors operate. When both groups of afferents were interrupted MAP, HR and PRA rose to significantly higher levels, implying that cardiopulmonary and arterial baroreceptor afferents interact in a sense of a non‐additive attenuation.
Renal and hormonal responses to atrial natriuretic peptide infusions in goats on high and low sodium intake
Authors: OLSSON K. , ERIKSSON L.
Published: December 2008

Renal and hormonal responses to atrial natriuretic peptide infusions in goats on high and low sodium intake. Acta Physiol Scand 130, 585–591. Received 7 December 1986, accepted 8 March 1987. ISSN 0001–6772. Department of Animal Physiology, Swedish University of Agricultural Sciences, Uppsala, Sweden and Department of Physiology, College of Veterinary Medicine, Helsinki, Finland.

Synthetic atrial natriuretic peptide (ANP) was infused intravenously (I μg min‐1; 60 min) in five goats during two series of experiments. For at least 4 weeks before the ANP infusions the goats received either no salt supplementation (= low sodium diet), or were given 16 g NaCl mixed with the food each day (Na = 274 mmol day‐1; high sodium intake). The goats were changed between the treatments at random. ANP infusions caused diuresis, natriuresis and haemoconcentration during both diets. The urinary Na excretion increased about four‐fold during the high sodium intake, and about 10 times during the low sodium intake. The urinary K excretion increased significantly during the low sodium diet, but decreased slightly during the high sodium intake. During both diets the K excretion became significantly lowered after the infusions. The mean glomerular filtration rate (GFR) was generally lower during the low sodium diet, but increased significantly during ANP infusions on both diets. The GFR returned to baseline immediately after the infusions, in contrast to urine flow and urinary Na excretion. Renal free water clearance increased slightly at the end of the infusion during the low sodium diet, but did not change during the high salt diet. Plasma renin activity (PRA) and plasma aldosterone concentration fell during ANP infusions in goats on the low sodium intake, but did not change significantly during the high sodium diet. These results indicate that the diuresis and natriuresis observed during intravenous ANP infusions in goats are mainly due to increased GFR. The haemoconcentration appears not to be secondary to fluid losses via the kidneys. The results support the concept that changed activity of the renin‐angiotensin‐aldosterone system is not a prerequisite for ANP‐induced natriuresis.
Beta‐endorphin and adrenocorticotropin response to supramaximal treadmill exercise in trained and untrained males
Authors: FARRELL P. A. , KJAER M. , BACH F. W. , GALBO H.
Published: December 2008

Beta‐endorphin and adrenocorticotropin response to supramaximal treadmill exercise in trained and untrained males. Acta Physiol Scand130, 619–625. Received 18 March 1986, accepted 6 March 1987. ISSN 0001–6772. Institute of Medical Physiology B, University of Copenhagen, Denmark, Department of Human Kinetics, University of Wisconsin‐Milwaukee and Department of Physiology, Medical College of Wisconsin, and Departments of Clinical Chemistry and Neuromedicine, Gentofte Hospital, Denmark.

The response of plasma β‐endorphin (β‐EP) and adrenocorticotropin (ACTH) was studied in seven well‐trained (T) young endurance athletes and seven untrained (UT) age‐ and weightdmatched males during treadmill exercise. Subjects ran continuously for 7 min at 60% Vo2max, 3 min at 100% Vo2max and 2 min at 110% Vo2max. Arterialized blood was obtained periodically from a cannulated heated (41 °C) hand vein. Plasma β‐EP was measured by radio‐immunoassay (RIA) which incorporated an antibody that did not cross‐react (< 1.5%) with β‐lipotropin. Plasma β‐EP was similar between groups at rest (T = 4.3±0.8 fmol ml‐1, mean ± SE, UT = 3.3 ± 0.6 fmol ml‐1) and did not change at the 60%±o2max stage. Beta‐endorphin significantly increased at 100% Vo2max with both groups responding similarly. A further increase occurred at 110% Vo2max (T = 10.8 + 2.0 and UT = 6.6+1.0 fmol ml‐1, P 0.05 for between group differences). This between group difference persisted I rnin after exercise when the highest β‐EP levels were reached (T = 18.7 ± 4.7 and UT = 12.8 ± 3.1 fmol ml‐l, P 0.05). Plasma ACTH responses were similar to β‐EP with the highest values (T = 61.5 ±7.2, UT = 45.7 ± 6.8 fmol ml‐1, P 0.05 for between group differences) occurring at I min post‐exercise. A positive correlation, r = 0.85, P 0.05, was found between β‐EP and ACTH using the I rnin post‐exercise values. The enhanced response of β‐EP and ACTH in T may indicate a training‐induced adaptation which increases the response capacity to extreme levels of stress.
Blood flow in skin, subcutaneous adipose tissue and skeletal muscle in the forearm of normal man during an oral glucose load
Authors: BULOW J. , ASTRUP A. , CHRISTENSEN N. J. , KASTRUP J.
Published: December 2008

Blood flow in skin, subcutaneous adipose tissue and skeletal muscle in the forearm of normal man during an oral glucose load. Acta Physiol Scand 130, 657–661. Received 7 November 1986, accepted 8 March 1987. ISSN 00014772. Department of Clinical Physiology/Nuclear Medicine, Bispebjerg Hospital and Hvidovre Hospital, Department of Medical Endocrinology, Hvidovre Hospital, and Department of Medical Endocrinology, Herlev Hospital, Copenhagen, Denmark.

Blood flow to the forearm, and the subcutaneous tissue and skin in the forearm were measured by strain gauge plethysmography, 133Xe‐elimination and Laser Doppler flowmetry during an oral glucose load (I g glucose kg‐I lean body mass) and during control conditions. The forearm blood flow remained constant during both experiments. Glucose induced a two‐fold vasodilatation in subcutaneous tissue. In skin, glucose induced a relative vasodilatation and later a relative vasoconstriction compared with control experiments. When estimated from forearm blood flow and subcutaneous and skin blood flows, muscle blood flow decreased about 20–30% during both experiments. Proximal nervous blockade did not abolish the glucose‐induced vasodilatation in subcutaneous tissue. In the glucose experiment, arterial glucose concentration increased to 7.8 ±1.17 mmol 1‐‐1 30min after the load was given and then decreased to 4.5 ±0.34 mmol 1‐‐1 at the end of the experiment. In the control experiments glucose concentration was constant. Arterial noradrenaline concentration increased significantly from 1.0±0.13 to about 1.5±0.3 nmol 1‐‐1 120 min after glucose and remained at this level during the experiment. Similarly adrenaline increased from 0.16 ±0.11 to about 0.4 ±o.16 nmol I‐1 180 min after glucose. It is hypothetized that the vasodilating effect of glucose in subcutaneous tissue is secondary to metabolic events connected to glucose uptake and energy deposition in adipose tissue.
Isoflurane hyperpolarizes neurones in rat and human cerebral cortex
Authors: BERG‐JOHNSEN J. , LANGMOEN I. A.
Published: December 2008

Isoflurane hyperpolarizes neurones in rat and human cerebral cortex. Acta Physiol Scand130, 679–685. Received 19 January 1987, accepted 10 March 1987. ISSN 0001–6772. Institute for Experimental Medical Research and Department of Neurosurgery, Ullevål University Hospital and Department of Neurosurgery, National Hospital, Rikshospitalet, Oslo, Norway.

The effect of the anaesthetic gas isoflurane was studied by intracellular recordings in neurones from rat hippocampal cortex and neurones from human neocortex in vitro. Anaesthetic concentrations of isoflurane abolished spontaneous activity and reduced synaptically evoked activity without rendering individual cells inexcitable or preventing evoked synaptic activity to increased afferent input. Induced epileptiform activity was not observed. Isoflurane reversibly hyperpolarized the cell membrane in a dose‐dependent manner, isoflurane 1.5, 3 and 5% causing 4±1, 6 ± 2 and 8±2 mV (mean ± SD) hyperpolarization, respectively. The hyperpolarization was accompanied by a reduction in the input resistance, 18 ± 3 % for 3 % isoflurane. The effects remained unchanged after synaptic transmission was blocked. Five experiments with intracellular recordings from human cortical neurones in vitro showed identical results.
Functional development of the visual system in normal and protein‐deprived rats. V. Specific cortical response and repetitive stimulation in adult rats
Authors: SJÖSTRÖM A. , CONRADI N. G. , ANDERSSON S. A.
Published: December 2008

Functional development of the visual system in normal and protein deprived rats. V. Specific cortical response and repetitive stimulation in adult rats. Acta Physiol Scand130, 705–711. Received 29 December 1986, accepted 16 March 1987. ISSN 0001–6771. Departments of Physiology and Pathology, University of Göteborg, Sweden.

Recent studies on the specific visual system have indicated that early induced protein deprivation results in an impaired transmission from cell to cell in the cortex. To further investigate cortical mechanisms the response to repetitive light flashes and to electrical stimulation of the optic tract (OT) and the dorsal lateral geniculate nucleus (dLGN) were examined. The first potential of the surface visual evoked response (VER) and the monosynaptic response to OT and dLGN stimulation showed similar sensitivity to repetitive stimulation in C and PD rats. In PD rats later activity was significantly more sensitive to repetitive stimulation than in controls. By using paired stimuli with a short inter‐stimulus interval, similar inhibitory mechanisms in PD and C rats were demonstrated. The results support the view that protein deprivation results in impaired cortical synaptic activation. The results are discussed in relation to previously described impairment at the cortical level in malnourished animals.
Functional development of the visual system in normal and protein‐deprived rats. VI. Evoked responses in adult rats, protein deprived in early life and nutritionally rehabilitated from weaning
Authors: SJÖSTRÖM A. , CONRADI N. G.
Published: December 2008

Functional development of the visual system in normal and protein‐deprived rats. VI. Evoked responses in adult rats, protein deprived in early life and nutritionally rehabilitated from weaning. Acta Physiol Scand130, 713–721. Received 29 December 1986, accepted 16 March 1987. ISSN 0001–6772. Departments of Physiology and Pathology, University of Göteborg, Sweden.

Previous studies have shown an increase in latency of the visual evoked response (VER) recorded from the cortical surface of adult rats subjected to protein deprivation (PD) during pre‐ and postnatal development. This alteration has been shown to originate mainly from the cortex itself. In the present study the possibility of normalizing such VER alterations by nutritional rehabilitation after early protein deprivation (R‐PD) was investigated. Male rats were subjected to pre‐ and early postnatal protein deprivation through their mothers. Nutritional rehabilitation was started from weaning. The rats gained weight rapidly compared with rats subjected to protein deprivation throughout postnatal development but never reached the weight of controls (C) of the same age. Food consumption in relation to body weight was similar to that of controls. Rehabilitation continued until adult age when neurophysiological experiments were performed. The VER recordings from the dorsal lateral geniculate nucleus (dLGN) showed latencies similar to those reported previously for adult C and PD rats. The latencies of onset and first peaks of the cortical response recorded from the surface were increased by 5–6 ms in R‐PD compared with C rats and hence similar to the latencies of adult PD rats. Intracortical responses to electrical stimulation in the dLGN were also similar to those of adult PD rats showing an normal onset latency but an increased latency of the peaks of the monosynaptic and late responses compared with C rats. The present results imply that the increased VER latencies noted in adult PD and R‐PD rats are due to changes installed by protein deprivation during early development since they can not be reversed by nutritional rehabilitation starting at weaning.
Melatonin reduces the production and secretion of prolactin and growth hormone from rat pituitary cells in culture
Authors: GRIFFITHS D. , BJØRO T. , GAUTVIK K. , HAUG E.
Published: December 2008

A culture of clonal tumour cells from rat pituitary gland that secrete both prolactin and growth hormone were used to investigate whether the pineal hormone melatonin can act directly on the pituitary gland to control prolactin production. Melatonin inhibition of prolactin and growth hormone production was significant but mild. Concentrations of between 10–8M and 10–8M reduced both prolactin and growth hormone production and prolactin secretion by 10–50%. 17β‐oestradiol (OE) and thyrotrophin‐releasing hormone (TRH) stimulated prolactin production but had no significant effect on growth hormone production. Melatonin reduced the effects of both of these compounds. Both TRH and vasoactive intestinal peptide (VIP) stimulated secretion of prolactin, and TRH also of growth hormone. Melatonin reduced these effects significantly. TRH and VIP increased cAMP production two‐ and 12‐fold, respectively. Melatonin had no effect on basal or stimulated cAMP production. The melatonin‐induced changes in prolactin and growth hormone production and secretion seen here do not approach the magnitude of the fluctuations seen in plasma in vivo. It is concluded that while melatonin does have a direct effect on the lactotroph in the regulation of prolactin production, its main physiological target must be elsewhere.
Parotid salivary flow in response to mechanical and‐gustatory stimulation in man
Authors: KJEILEN J. C. JENSEN , BRODIN P. , AARS H. , BERG T.
Published: December 2008

To examine further the role of the oral receptors in the masticatory–salivary reflex, a study with eight subjects was performed. The influence on mean parotid salivation of combined alterations in frequency and force of chewing and length of the chewing object was evaluated by group comparison. Salivary flow rate was recorded using a sensitive micromanometer, and the frequency (12, 60 and 90 cycles min‐1) and force of chewing (to and 40% of maximum) were controlled by a metronome and masseter muscle EMG, respectively. The maximum instantaneous flow and the latency of the masticatory‐salivary reflex were examined in three subjects. For comparison with mean salivation rate during chewing, gustatory stimulation was performed with 0.5 or 5.0% citric acid. The masticatory–salivary reflex was mainly ipsilateral, and depended upon having an object between the teeth. Salivation increased with increases in frequency and force of chewing and with the number of teeth involved, each parameter of chewing having the greatest influence when increased from a low level of action. The salivation response to chewing showed two phases; the first, presumably due to contraction of the myoepithelial cells, had a latency of 0.2–0.4 S, while the second phase occurred about r s later. Our results support the hypothesis that the periodontal mechanoreceptors have a major role in the parotid response to chewing. Application of 0.5 and 5.0% citric acid on the back of the tongue induced dose‐dependent parotid secretions, significantly higher than those of chewing. A negative correlation was found between the maximum fluid outputs during chewing and 5.0% citric acid stimulation.
Polyamine metabolism in rat parotid gland after duct ligation
Authors: NILSSON B.‐O. , EKSTRÖM J. , ROSENGREN E.
Published: December 2008

Parotid ducts were ligated unilaterally in rats for periods from 6 h to 5 months. A slight increase in gland weight was observed during the first 24 h; thereafter, the weight gradually fell, being less than 5o% of controls at 5 months. The activity of the putrescine‐forming enzyme, ornithine decarboxylase (ODC), increased with peak values by 3 days and 3 weeks. However, the putrescine content had already reached its highest value by 24 h. A notably marked reduction of spermidine and spermine contents was observed by 1 day after ligation and throughout the whole time of observation. The results suggest that an inverse polyamine metabolism occurred, that is, spermine converts to spermidine which in turn converts to putrescine.
Effect of arterial pH and PCO2on biliary HCO‐3secretion in the pig
Authors: GROTMOL T. , BUANES T. , RÆDER M. G.
Published: December 2008

The purpose of the present study was to examine the effect of changes in arterial pH and PCO2on biliary HCO‐3secretion. This was done in order to further characterize the various ion transport mechanisms considered responsible for biliary HC3secretion in the pig. Experiments were performed on two groups of six pigs. In both groups arterial pH was varied in steps from pH 7.40 to 7.40, both at PCO25.5 PCO2and PCO2, 10 kPa. In group I (n= 6), data were obtained on the effect of arterial pH and PCO2on ductular PCO2secretion in bile acid depleted (cholestyramine pretreated), secretin‐infused pigs. In group II (n= 6), the effect of pH and PCO2on canalicular HCO‐3secretion was studied in ursodeoxycholic acid (UDCA)‐infused pigs (3 μml min‐1kg‐1body wt). In group I, biliary HCO‐3secretion exhibited PCO2‐ dependent, positive straight line relationships to arterial pH. An increment in biliary HCO‐3secretion of 17 (11–24)% was seen during high PCO2at pH 7.40. In group II, biliary HCO‐3secretion exhibited PCO2‐dependent, positive curvilinear relationships to arterial pH. A median increment in HCO‐3secretion of 37 (20–62)% was seen during elevated PCO2at arterial pH 7.40. The linear dependence of ductular HCO‐3secretion on arterial pH and the effect of elevated HCO‐3on PCO2secretion fit well with findings in other epithelia, where proton transport is thought be driven by a proton pump. A computer simulation provided evidence suggesting that secretin‐dependent HCO‐3secretion does not involve the action of a Na+/H+ion exchanger—in contrast to UDCA‐dependent HCO‐3secretion. It is concluded that ductular and canalicular HCO‐3secretion could be mediated by a proton pump and a Na+/H+ion exchanger in addition to canalicular HCO‐3secretion due to solvent drag and diffusion, respectively.
Fatigue and endurance of lower extremity muscles in relation to running velocity at OBLA in male orienteers
Authors: JOHANSSON C. , GERDLE B. , LORENTZON R. , RASMUSON S. , REIZ S. , FUGL‐MEYER A. R.
Published: December 2008

At three occasions during a year, the ratio of contractional work (output)/integrated electromyographic activity (input), that is, CW/iEMG, was measured during repetitive maximum isokinetic manoeuvres for m. quadriceps and m. triceps surae in male elite orienteers. Running velocity at the onset of blood lactate accumulation (Vobla), which was considered as a measure of running performance, and maximal oxygen uptake (VO2max) were analysed at each test. Type and amount of training were continuously registered. For m. quadriceps there was a decline in CW/iEMG during the first 30 manoeuvres, followed by an unchanged plateau level. In contrast, m. triceps surae showed a plateau level of virtually unaltered CW/iEMG ratio from the start to the end of the experiment. The differences might be explained by structural causes, but also by local muscle adaptation to training. The plateau level of CW/iEMG of m. quadriceps was positively correlated to VO2max. An increase in the plateau level of CW/iEMG was found for both tested muscle groups after the winter training period (mainly low intensity road running) when both Vobla and VO2OBLA increased. During the competition period (mainly high intensity forest running), the whole group increased while some orienteers lowered their Vobla. During this period, no changes in the plateau level of CW/iEMG of any muscle group or in VO2OBLA occurred. The changes in the plateau level of CW/iEMG might express local muscle adaptations to changes in running technique and aerobic/anaerobic demands during low intensity road running versus high intensity forest running.
Glucose stimulates the entry of Ca2+ into the insulin‐producing β cells but not into the glucagon‐producing α2 cells
Authors: WESSLÉN N. , PIPELEER D. , VAN De WINKEL M. , RORSMAN P. , HELLMAN B.
Published: December 2008

Rat pancreatic β and α2 cells were purified by autofluorescence‐activated cell sorting and used for electrophysiological patch clamp studies and measurements of the initial uptake of 45Ca. Both β and α2 cells were electrically active, the action potentials of the latter cells also were detected in the absence of glucose. Furthermore, α2 cells differed from β cells in lacking a glucose‐sensitive K+ channel with a single channel conductance of 50–60 pS (in symmetric 140 mm K+ solutions). The rate of Ca2+ entry into the α2 cells was slower than that into the β cells, being equivalent to 0.2 mmol, kg‐1 dry wt min‐1. Whereas raising the glucose concentration to 20 mm significantly increased the amount of Ca2+entering the β cells, the sugar was without effect on Ca2+ entry into the α2 cells.
Low potency of Ca antagonists in smooth muscle from different levels of the respiratory tract
Authors: BENGTSSON B. , KHAN A. R. , WEIBER R.
Published: December 2008

Respiratory smooth muscle at different levels of the respiratory tract was isolated from rabbit, rat and guinea‐pig and incubated with the Ca antagonists, verapamil, D‐600, felodipine, and nifedipine. There was no effect of the Ca antagonists when added on top of an already developed contraction. When added before the contractile agent at high concentrations (10–100 μ m) the Ca antagonists reduced the contractions. Lanthanum (z mm) was considerably more effective to prevent contractions than the Ca antagonists. Preparations from the trachea and bronchus responded in all animals, whereas the third generation bronchus from rat and guinea‐pig failed to contract and that from rabbit showed very weak contractions. The failure to contract was not specific for the agonist, as depolarization with isotonic potassium solution (124 mm) did not evoke contractions either. Microscopic investigation showed well‐developed smooth muscle in the trachea and main bronchus of the rat, whereas the muscle of the third generation bronchus was inhomogenous with scattered groups of muscle cells.
Glycogen and glycogen‐hydrolysing lysosomal enzyme activity in mouse liver: effects of fasting, adrenoceptor antagonism and insulin‐induced hypoglycaemia
Authors: SKOGLUND G. , AHRÉN B. , RERUP C. , STENSTRÖM A. , LUNDQUIST I.
Published: December 2008

Whereas the phosphorolytic breakdown of liver glycogen is known to be of great physiological importance, the functional role of the hydrolytic glycogenolysis in the lysosomal system is less well understood. In the present study the effects of fasting, α‐ and β‐adrenoceptor antagonism and insulin‐induced hypoglycaemia on liver lysosomal glycogen‐hydrolysing enzyme activity were investigated in mice. In freely fed mice the glycogen‐hydrolysing activity (acid amyloglucosidase) was only 50% of the maltose‐hydrolysing activity (acid maltase). Starvation for 24 h reduced the acid amyloglucosidase activity by approximately 30% (P > 0.001), whereas the activities of acid maltase, acid phosphatase and β‐glucuronidase appeared unaffected. N‐acetyl‐β‐d‐glucosaminidase activity was moderately (20%; P > 0.01) enhanced by fasting. Thus, liver lysosomal enzyme activities may change independently of each other during fasting. Further, during short‐term hypoglycaemic conditions (45 min) induced by endogenous or exogenous insulin, the activity of liver acid amyloglucosidase was found to be moderately reduced (15–20%). Blockade of α‐ and β‐adrenoceptors by phentolamine and propranolol did not result in any apparent influence on acid amyloglucosidase activity except for the indirect effect exerted by the phentolamineinduced hypoglycaemia. A moderate negative correlation (r=–0.51; P > 0.001) between total liver glycogen concentration and acid amyloglucosidase activity was observed in a series of 43 freely fed NMRI mice. Our data show that in mouse liver the acid maltase activity predominates over the acid amyloglucosidase activity. Further, the results suggest that liver lysosomal hydrolytic glycogenolysis may be of little importance for the acute energy needs of the body during hypoglycaemic conditions, such as 24 h fasting or short‐term insulin‐induced hypoglycaemia. The mechanisms of interaction between cytoplasmic and lysosomal glycogen pools merit further investigation.
Renal and cardiovascular effects of atrial natriuretic peptide in Wistar‐Kyoto and spontaneously hypertensive rats during a chronic salt loading
Authors: GRADIN K. , PERSSON B.
Published: December 2008

Spontaneously hypertensive rats (SHR) and Wistar‐Kyoto (WKY) rats were maintained on tap water or 1.5% NaCl for 3 weeks. During the high sodium regime 24‐h urinary sodium excretion increased 10‐fold and the basal blood pressure increased in the SHR. After 3 weeks the rats received arterial (carotid artery), venous and bladder catheters (suprapubic). Saline was infused continuously and in conscious rats atrial natriuretic peptide (α‐hANP) was administered as bolus injections (8 and 16 nmol kg‐1) and the blood pressure and heart rate and the urinary excretions of sodium, potassium (flame photometry), noradrenaline and dopamine (HPLC) were followed at 5‐min intervals. The administration of ANP caused a short‐lasting blood pressure reduction, tachycardia, diuresis and increased urinary excretions of sodium, potassium, noradrenaline and dopamine. The blood pressure responses to ANP did not differ between the rat strains, irrespective of the diet. The natriuresis and diuresis to ANP was reduced in animals on a high sodium diet, especially in the SHR. This may be interpreted as a down‐regulation of target organ responsiveness to ANP during a high sodium diet and the inappropriately large decrease in the responsiveness that was observed in the SHR may be related to increase in blood pressure during the high sodium diet.
Possible reflection of intracellular calcium binding in the divergent pattern of relaxation in rat and rabbit uterus
Authors: BATRA S. , BENGTSSON B. , POPPER L. D.
Published: December 2008

The mechanical responses to potassium of the rabbit and rat uterus were different. The force of a potassium‐induced contracture showed a rapid decline in the rabbit uterus, whereas it was fully maintained for a long period in the rat uterus. The increase in 45Ca influx following exposure to high KCl was substantial and similar (0.3 mmol kg‐1) in both rat and rabbit uterus. Calcium uptake in post nuclear supernatant (PNS) from the rat myometrium was significantly lower than that from the rabbbit myometrium in both the rate and capacity of uptake. This uptake was reduced to about 10% in the presence of sodium azide in PNS from both rat and rabbit myometria. Both the rate and capacity of calcium uptake by mitochondria isolated from PNS of rat myometrium were considerably lower than that by rabbit myometrial mitochondria. Microsomes isolated from rat and rabbit PNS had very low capacity for calcium uptake compared with mitochondria. No difference was found in the rate or the capacity of uptake between the rat and the rabbit myometrial microsomes. The data support the argument for a role of mitochondria in myometrial relaxation and further provide evidence for a considerable species difference in calcium uptake by myometrial mitochondria.
Mechanical work and efficiency in ergometer bicycling at aerobic and anaerobic thresholds
Authors: LUHTANEN P. , RAHKILA P. , RUSKO H. , VIITASALO J. T.
Published: December 2008

Internal and external mechanical work, energy consumption and mechanical efficiency were studied in constant‐load ergometer bicycling at five different power outputs below, equal to, and above the aerobic (AerT) and anaerobic (AnT) thresholds. The gross, net and true efficiencies of the whole body in five male subjects were calculated. The work against the external load was defined as the external mechanical work. The internal mechanical work was calculated as the sum of the increments of kinetic and potential energy in all body segments by using methods of film analysis. Total energy consumption was measured by combining aerobic and anaerobic energy production. When the power output of the bicycle ergometer was increased from 146+15 to 283 ± 17 W, oxygen consumption increased from 2.20 ± 0.98 to 4.22 ± 0.201 min‐1 (P < 0.001), while the oxygen consumption at rest was 0.30 ± 0.03 l min‐1. The concentration of blood lactate increased from 2.2 ± 0.4 at the lowest work load to 8.6 ± 1.2 mmol 1‐1 at the highest work load (P < 0.001). The amount of external work done per revolution increased from 139 ± 20 to 277 ± 29 J (P < 0.001), while the amount of internal work per revolution remained almost constant (56 ± 12 J). The gross efficiency in the present study was 17–20%, net efficiency 18–22% and true efficiency 21–30%, respectively. The highest gross and net efficiencies were reached at the AerT. The lowest efficiencies were obtained at highest work load. Oxygen uptake and total energy consumption were significantly higher and true efficiency lower at the AnT than AerT (P < 0.01).