bluuebunny/crossref_metadata_2025 huggingface dataset:
On the relationship between urinary PGE2and PGF2αexcretion rates and urine flow, osmolar excretion rate and urinary osmolality in anesthetized rats
Authors: LEYSSAC PAUL P. , CHRISTENSEN POUL
Published: December 2008

A strong inverse relationship was found between the excretion rates of the prostaglandins PGE2and PGF2αand urine flow (and osmolar excretion rate) over a range of urine flow rates from 1.5 to 40 μl·min‐1·g kidney weight‐1, covering spontaneous variations and isotonic saline diuresis. These results suggest the operation of a negative feedback mechanism by which the diuretic action of the prostaglandins, as part of a defence system, counteracts excessive oliguria. PGE2excretion did not correlate with either urinary kallikrein excretion or plasma renin concentration. When the concentrating mechanism was interfered with by reducing renal perfusion pressure to, or below 65 mmHg, and vasopressin was given i.v. PGE2excretion rate roughly parallelled urine—and probably medullary interstitial osmolar activity. However, in hydropenic rats there was no correlation between urine osmolality (Uosm) and PGE2excretion over a range of osmolalities from 500 to 2500 mOsm · kg‐1, nor any relationship between ΔUosmand ΔPGE2excretion. Thus, a high interstitial osmolar activity appears to be a prerequisite for the activation of PG‐synthesis in the renal medulla, but another (other) yet undefined factor(s) play the major role as (a) determinant(s) for PG‐excretion in vivo.
Plasma colloid osmotic pressure in venous blood from the human foot in orthostasis
Authors: NODDELAND HARALD , AUKLAND KNUT , NICOLAYSEN GUNNAR
Published: December 2008

Several theories could explain the slow rate of edema formation in the feet of sitting or standing man. One possible mechanism is a rise in local plasma colloid osmotic pressure (πp). We measured πpin blood from superficial veins of warm and cold feet during ortho‐stasis. The difference in venous (πp) between the foot and the arm averaged 12.8 mmHg (range 9.4–16.1 mmHg) in subjects sitting in a cold room. Hemoconcentration was also reflected as increased hematocrit. These findings support the view that a local increase of (πp) in foot capillaries contributes considerably to edema prevention during orthostasis.
In vivo studies of the motility of the isthmic segment in the perfused rabbit oviduct
Authors: STRÖM C. , EDIN R. , DAHLSTRÖM A. , AHLMAN H.
Published: December 2008

The motility of the isthmic segment of the rabbit oviduct was studied in vivo using a perfusion model. The transisthmic flow of saline (38°) was recorded at constant inflow pressures uni‐ or bilaterally. In untreated control animals there was a high resistance to flow within the isthmic segment. 12, 24, 48 and 72 h after induced ovulation by i.v. injection of human choriongonadotropin (HCG; 50 IU) the resistance gradually declined. No synchronous spontaneous motility pattern was recorded from the oviducts of any animal. When adrenergic agonists were administered 48 h after HCG, either intraluminally or intravenously, flow ceased after the α‐adrenoceptor agonists noradrenaline (2–50 μm) or phenylephrine (2–10 μg), while an increased flow was recorded after the β‐adrenoceptor agonist isoprenaline (5–100μg). The duration of the motoreffects varied dose‐dependently. Therefore it seems as if the motility of the isthmic segment is under adrenergic control, at least 48 h after HCG, with contractions caused by α‐adrenoceptor stimulation and dilations caused by β‐adrenoceptor stimulation. The perfusion model used appears to be suitable for studying the adrenergic control of the isthmic segment after appropriate pretreatment with HCG.
Vibrotactile thresholds in non‐Pacinian mechanoreceptive afferents: the importance of temporal parameters
Authors: PERTOVAARA ANTTI , HÄMÄLÄINEN HEIKKI
Published: December 2008

Vibrotactile thresholds of non‐Pacinian mechanoreceptive afferents (RA, SAI, SAII) were determined as a function of stimulus duration (100–800 ms) at three frequencies (20–240 Hz). Altogether 64 units innervating the hairy skin of the cat were tested. At all frequencies SAII units had the lowest thresholds whereas SAI units had the highest thresholds. At all frequencies and in all unit populations the absolute thresholds (1 impulse/stimulus train) were independent of stimulus duration, whereas the tuning thresholds (1 impulse/cycle) were elevated as a function of increasing stimulus duration. The present results suggest that the detection threshold decreases as a function of increasing stimulus duration are not based on peripheral properties of non‐Pacinian mechanoreceptors.
Evidence for feedback mediated reduction of glomerular filtration rate during infusion of acetazolamide
Authors: PERSSON A. ERIK G. , WRIGHT FRED S.
Published: December 2008

Systemic administration of acetazolamide (ACZ) causes glomerular filtration rate (GFR) to fall. Clearance and micropuncture experiments were done to define the mechanism of this drug effect. When rats were infused with ACZ intravenously, kidney GFR fell by 30% and single nephron (SN) GFR (measured by collecting distal tubule fluid) fell by 23%. Changes in arterial blood pressure, arterial pH, extracellular fluid volume, and proximal tubule pressure were not sufficient to account for the decrease in GFR. When SNGFR was measured by collecting proximal tubule fluid, with the loop of Henle having been blocked for 2–5 min, SNGFR was higher than the distally measured value and was not different than control. The results are consistent with the fall in GFR being caused by activation of the tubulo‐glomerular feedback mechanism.
Effects of insulin on serum gastrin concentrations, gastric acid secretion and histamine mobilization in the rat
Authors: EKELUND M. , HÅKANSON R. , HEDENBRO J. , LIEDBERG G. , LUNDQUIST I. , REHFELD J. F. , SUNDLER F.
Published: December 2008

Small doses of insulin (<1.25 U/kg) caused hypoglycemia, stimulated gastric acid secretion slightly, activated gastric mucosal histidine decarboxylase moderately, and enhanced the pentagastrin‐induced activation of histidine decarboxylase. Large doses of insulin (>2.5 U/kg) caused marked hypoglycemia and hypergastrinemia. Moreover, it lowered gastric mucosal histamine concentration and greatly activated histidine decarboxylase. Gastric acid secretion was not stimulated. Pentagastrin‐stimulated acid secretion was blocked and histamine‐stimulated secretion slightly inhibited. Combined administration of insulin and glucose prevented the acid response (insulin dose 0.6 U/kg) and the activation of histidine decarboxylase but not the hypergastrinemia (2.5 U/kg). Paradoxically, combined treatment with insulin and glucose did not prevent pentagastrin from activating histidine decarboxylase. Glucose alone raised the serum gastrin concentration in both unoperated and vagotomized rats. The histidine decarboxylase activity was not raised. Glucose inhibited the pentagastrin‐induced release of histamine greatly but inhibited the pentagastrin‐induced enzyme activation only moderately. In antrectomized rats, large doses of insulin (>1.25 U/kg) had no effect on the serum gastrin concentration but stimulated gastric acid secretion in contrast to what was the case in unoperated rats. Glucose prevented the acid response to insulin. The gastric histidine decarboxylase was not activated by insulin following antrectomy. In vagally denervated rats, insulin (5 U/kg) increased the serum gastrin concentration slightly but did not raise the histidine decarboxylase activity. We interpret the results as follows: With small doses of insulin the gastric secretagogue effect is attributable mainly to vagal nerve stimulation evoked by the hypoglycemia. With large doses of insulin there is no acid response. The effects on the parietal cells of the ensuing hypergastrinemia are counteracted by an unknow mechanism, which however does not prevent gastrin from releasing gastric histamine and stimulating gastric histidine decarboxylase. The insulin‐induced release of gastrin is not elicited exclusively through vagal excitation by hypoglycemia, since insulin releases gastrin also after vagotomy and after glucose administration. The great enzyme‐activating effect of insulin is a consequence of gastrin release. In addition, however, insulin seems to enhance the responsiveness of the enzyme‐containing cells to gastrin. Insulin is a poor substitute for vagal excitation in that it exerts a number of actions which are unrelated to vagal excitation.
Characterization of two substance P antisera
Authors: BRODIN ERNST , NILSSON GÖRAN , FOLKERS KARL
Published: December 2008

The cross reactivity of two currently used substance P (Sp) antisera (K 16 and K 25) with various analogues of SP, partial sequences of SP and other naturally occurring peptides were tested in a radioimmunoassay system. Both antisera were found to be C‐terminal directed, this tendency being most pronounced for antiserum K16. The capacity of antiserum K 25 to bind various SP‐related peptides correlated to the previously described biological activity of these peptides on the isolated guinea pig ileum. The results thus indicate that this antiserum binds to a biologically active part of the SP‐molecule.
Permeability of fenestrated capillaries in the isolated pig pancreas, with effects of bradykinin and histamine, as studied by simultaneous registration of filtration and diffusion capacities
Authors: HARALDSSON B. , RIPPE B. , MOXHAM B. J. , FOLKOW B.
Published: December 2008

Combining an isogravimetric technique and a colorimetric ‘on‐line’ method (Rippe & Stage 1978). filtration capacity (CFC) and diffusion capacity (PS) were simultaneously measured in the maximally vasodilated fenestrated capillary bed of isolated, artificially perfused pancreatic glands in 12 juvenile pigs. Both CFC and PS for Cr‐EDTA were about 20 times greater than in the ‘continuous’ capillary bed of skeletal muscle. With perfusate flow rates of 250 ml/min × 100 g during isogravimetry, PS‐Cr‐EDTA averaged 110± 10.0 (S.E.) ml/min ±100 g, and diffusion limitation occurred first at flow rates above 300 ml/min ± 100 g. CFC was independent of flow rate and averaged 0.641+0.027 ml/minx 100 g ± mmHg. The parallel augmentation of PS‐Cr‐EDTA and CFC in the fenestrated capillary bed compared with continuous ones seems to reflect both a higher number of capillaries per unit tissue and an increased number of ‘small pores’ per unit capillary surface, whilst the ‘large pore system’ appears to be similar. Following bradykinin or histamine infusion, results were similar to those for continuous capillaries (e.g. Rippe, Kamiya & Folkow 1978). Thus, without further vasodilatation CFC increased 3‐fold while PS‐Cr‐EDTA increased only some 25%, and subsequent isoprenaline infusion reversed these effects. Previous studies on continuous capillaries indicate that histamine‐type agents act by opening additional ‘large pores’ in the venular exchange sections (cf. Rippe & Grega 1978, Svensjo 1978). while P‐adrenergic agonists block this effect. The results further suggest that the fenestrae are not involved in these bradykinin‐histamine effects, but rather function as a ‘high‐density, small pore population’.
Abolished relationship between pancreatic HCO‐3 secretion and arterial pH during carbonic anhydrase inhibition
Authors: RRDER MORTEN , MATHISEN ØYSTEIN
Published: December 2008

After acetazolamide administration, CO2 hydration in pancreatic cells would be slow and might become a rate‐limiting factor to pancreatic HCO‐3 secretion. Correspondingly, pancreatic HCO‐3 secretion—normally pH dependent—would become slow and pH‐independent. However, acetazolamide would not be expected to interfere with the capacity of the secretory mechanism to generate a proton potential gradient between pancreatic cells and interstitial fluid. These predictions were examined in 5 anesthetized, secretin infused (2.7 C. U./kg b. wt. h‐1) pigs. Pancreatic juice was collected from a catheter in the pancreatic duct. Arterial pH was varied through i.v. HCI and NaHCO3 infusions and CO3 addition to inspired air. Before acetazolamide, HCO‐3 secretion varied with plasma pH and averaged 298±30 μmol/min at control arterial pH. Acetazolamide (150 mg/kg, i.v.) reduced HCO‐3 secretion to 84±12 μmol/min and rendered secretion independent of arterial pH between pH 7.6 and pH 7.0. It is concluded that acetazolamide imposes a pH‐independent transport maximum on pancreatic HCO‐3 secretion, but does not reduce the capacity of the secretory mechanism to sustain a proton potential gradient between cells and interstitial fluid.
Ultrastructural observations in the rat ileal mucosa of possible epithelial “taste cells” and submucosal sensory neurons
Authors: NEWSON B. , AHLMAN H. , DAHLSTRÖM A. , NYHUS L. M.
Published: December 2008

Electronmicroscopical studies of the rat ileum have demonstrated the presence of submucosal neuronlike cells located just under the basal lamina of intestinal crypts. These cells had dendrite‐like processes and frequently made contacts with adjacent submucosal nerve terminals. Furthermore, within the mucosa epithelial ‘clear’ cells with apical cytoplasmic processes into the gut lumen and basal cytoplasmic processes extending underneath adjacent epithelial cells were demonstrated. The ‘clear’ cells were devoid of secretory granules, as e.g. endocrine cells. and had a morphological resembiance to taste cells. Occasionally the ‘clear’ cells made contacts with submucosal nerve tcrminals. The possibility that the ‘clear’ cells and submucosal neuronlike cells represent a receptive function within the intestine is discussed.
Diet induced changes in sympatho‐adrenal activity during submaximal exercise in relation to substrate utilization in man
Authors: JANSSON E. , HJEMDAHL P. , KAIJSER L.
Published: December 2008

In order to study how the diet may influence sympatho‐adrenal activity during exercise, 7 subjects were examined at rest and during submaximal exercise (25 min at 65 % of °O2max) on two occasions. The first occasion was preceded by 5 days on a carbohydrate poor diet (5% carbohydrate, 72% fat and 23% protein) and the second one by 5 days on a carbohydrate rich diet (78 % carbohydrate, 8 % fat and 14% protein) with the same energy content. Oxygen uptake, respiratory exchange ratio (R), heart rate and arterial plasma concentrations of adrenaline, noradrenaline, dopamine, insulin, glucose, lactate, free fatty acids (FFA), glycerol and β‐hydroxybutyrate were measured at rest and during exercise. Oxygen uptake and heart rate during exercise were higher and R was lower after the carbohydrate poor than after the carbohydrate rich diet. During exercise the arterial plasma concentrations of FFA, glycerol and β‐hydroxybutyrate were higher after the carbohydrate poor than after the carbohydrate rich diet whereas concentrations of insulin and lactate were lower. At rest arterial plasma noradrenaline and adrenaline levels were similar on the two diets (0.70±0.31 nM noradrenaline and 0.35±0.32 nM adrenaline on the carbohydrate rich diet, mean values ± SD). Exercise induced increases in noradrenaline were more pronounced after the carbohydrate poor than after the carbohydrate rich diet (12.42±3.41 vs. 7.45±2.68 at 25 min of exercise,p<0.001). A similar, although more variable accentuation of exercise induced increases in adrenaline was found. It is concluded that, when compared to a carbohydrate rich diet, a carobohydrate poor diet increases the relative contribution of fat to oxidative metabolism and increases the sympatho‐adrenal response to exercise. Stimulation of lipolysis by sympatho‐adrenal mechanisms might be of importance for the substrate availability when carbohydrate intake is low.
Heterogeniety in regulation of glomerular function
Authors: ERICSON A.‐C. , SJÖQUIST M. , ULFENDAHL H. R.
Published: December 2008

The aim was to study differences in filtration driving forces and glomerular filtration rates between superficial and deep nephrons when urine flow rate was altered at the macula densa region. In young rats stop‐flow pressures and single nephron glomerular filtration rates (SNGFR) were measured in the superficial proximal tubules and in the loops of Henle in the papilla. SNGFR was also measured with a modified Hanssen technique. The stop‐flow pressures of superficial nephrons amounted to 30.9±0.8 mmHg (mean ± SE) and those of juxtamedullary nephrons to 52.2±1.6 mmHg. In the stop‐flow condition the net driving filtration forces were calculated to be about 19 mmHg and 50 mmHg for the superficial and deep glomeruli, respectively. In free flow conditions both net driving forces were calculated to be 19 mmHg. The micropuncture technique gave a SNGFR value for superficial nephrons of 29.6±2.9 and for deep nephrons of 84.1±8.5 nl±min‐1 g‐1 kidney weight (KW). With a modified Hanssen technique the corresponding values were 25.8±3.3 and 27.7±2.9 nl. min‐1.g‐1KW. The tubuloglomerular feedback mechanism is considered to have a powerful regulatory influence on the glomerular filtration rate of deep nephrons.
Effects of sympathetic stimulation on cerebral and ocular blood flow Modification by hypertension, hypercapnia, acetazolamide, PGI2 and papaverine
Authors: BEAUSANG‐LINDER MARIANNE
Published: December 2008

The effect of unilateral, electrical stimulatio of the cervical sympathetic chain in rabbits anesthetized with pentobarbital sodium and vasodilated by hypercapnia, acetazolamide, papaverine or PGI2 was investigated to determine to what extent the sympathetic nerves to the brain and the eye cause vasoconstriction and prevent overperfusion in previously vasodilated animals. Evans blue was given as a tracer for protein leakage. Blood flow determinations were made with the labelled microsphere method during normotension and acute arterial hypertension. Hypertension was induced by ligation of the thoracic aorta and in some animals metaraminol or angiotensin was also used. Acetazolamide caused a two to threefold increase in cerebral blood flow (CBF) and hypercapnia resulted in a fivefold increase. CBF was not markedly affected by papaverine or PGI2. In the choroid plexus, the ciliary body and choroid, papaverine and hypercapnia caused significant blood flow increases on the control side. Sympathetic stimulation induced a 12 % blood flow reduction in the brain in normotensive, hypercapnic animals. Marked effects of sympathetic stimulation at normotension were obtained under all conditions in the eye. In the hypertensive state the CBF reduction during sympathetic stimulation was moderate, but highly significant in hypercapnic or papaverine‐treated animals as well as in controls. Leakage of Evans blue was more frequently seen on the nonstimulated side of the brain. In the eye there was leakage only on the control side except in PGI2‐treated animals where 2 rabbits had bilateral leakage.

The effect of sympathetic stimulation on the blood flow in the cerebrum and cerebellum in vasodilated animals seems to be small or absent if the blood pressure is normal. In the eye pronounced vasoconstriction occurs under these conditions. In acute arterial hypertension sympathetic stimulation protects both the cerebral and ocular barriers even under conditions of marked vasodilation.
Changes in cadaverine and putrescine metabolism in the mouse kidney induced to growth by an anabolic steroid
Authors: ANDERSSON ANNE‐CHARLOTTE , HAMMAR LENA , HENNINGSSON STIG , LÖWENDAHL GUNNAR OSKAR
Published: December 2008

The formation of cadaverine and putrescine was studied in the kidneys of gonadectomized male mice stimulated to growth by nandrolone. an anbolic steroid with low androgenic activity. Administration of nandrolone resulted in an increased kidney weight and elevated activities of lysine and ornithine decarboxylase (assayed by measurement of the formation of 14CO2 from the I‐14C‐labelled amino acids). The responses were dose and time dependent. The elevated enzyme activities were reflected by an increased endogenous kidney content of cadaverine and putrescine as well as in an increased urinary excretion of the diamines. Further, the kidney content and the urinary excretion of the polyamines sper‐midine and spermine were elevated on nandrolone treatment. Fractionation of kidney extracts on pore gradient electrophoresis revealed an apparent molecular weight of about 95000 Daltons of the lysine decarboxylase as well as of the ornithine decarboxylase. On electrofocusing it was evident that both enzymes were present as more than one isoelectric form. However, the main form in both cases focused at a pH of about 5.0.
On the mechanism by which theophylline inhibits histamine release from rat mast cells
Authors: SYDBOM ANITA , FREDHOLM BERTIL B.
Published: December 2008

Theophylline (2.5 mM) did not influence the spontaneous release of histamine but inhibited histamine release induced by antigen, compound 48/80 or phosphatidylserine. The effect on 48/80‐induced histamine release could not be reversed by increasing extracellular Ca2+. Exogenous adenosine (10‐‐8to 10‐‐4M) did not influence spontaneous histamine release or 48/80‐induced release but potentiated antigen‐induced release. The adenosine potentiation was competitively inhibited by theophylline in concentrations (10‐‐5to 10‐‐4M) lower than those required to inhibit antigen‐induced histamine release in the absence of adenosine. In order to see if endogenous adenosine levels are high enough to potentiate an anaphylactic histamine release in vivo. adenosine was determined in mast cell incubates and in plasma from 4 different strains of rat. The levels were 0.18 to 0.99 μM in plasma, which is sufficient to cause significant potentiation of histamine release, but only 3×10‐‐8M in mast cell incubates. Theophylline (2.5 mM) increased cAMP levels about 100%. whereas adenosine (10‐‐5) had little effect on cAMPand cGMP levels. HOWever, when incubated together, adenosine could inhibit the theophylline‐induced increase in cAMP levels but not the inhibition of histamine release. It is concluded that the effect of low concentrations of theophylline could be due partly to antagonism of adenosine effects. In addition. in higher doses, theophylline appears to exert an inhibitory action that is unrelated to cyclic nucleotides, extracellular calcium and adenosine.
Effect of frequency of growth hormone administration on longitudinal bone growth and body weight in hypophysectomized rats
Authors: JANSSON JOHN‐OLOV , ALBERTSSON‐WIKLAND KERSTIN , EDÉN STAFFAN , THORNGREN KARL‐GÖRAN , ISAKSSON OLLE
Published: December 2008

JANSSON, J.‐O., ALBERTSSON‐WIKLAND, K., EDÉN, S., THORNGREN, K.‐G. and ISAKSSON, O.: Effect of frequency of growth hormone administration on longitudinal bone growth and body weight in hypophysectomized rats. Acta Physiol Scand 1982, 114:261–265. Received 11 May 1981. ISSN 0001–6772. Department of Physiology, University of Göteborg and Department of Orthopaedic Surgery, University of Lund, Sweden.

The effect of frequency of growth hormone (GH) administration on longitudinal bone growth and body weight was studied in hypophysectomized rats. Replacement therapy with 3 different doses of human GH [(hGH) Crescormone®] was started 10–14 days after hypophysectomy and was continued for 5 days. Longitudinal bone growth, as measured by the tetracycline method, and body weight were determined during the injection period. With a daily replacement dose of 128 μg of hGH body weight gain and longitudinal bone growth were significantly higher when the hormone was injected 4 and 8 times per day compared with animals receiving the hormone in one daily injection. When the dose of hGH was 32 or 8 μg per day, longitudinal bone growth and body weight gain were more pronounced in animals receiving the hormone 2 and 4 times per day compared with animals receiving the hormone one or 8 times per day. The results of the present study demonstrate that the frequency of GH administration influence body growth. The findings suggest that the secretory pattern of GH influence the growth rate under in vivo condition.
Electrotonic properties of motor nerve terminals
Authors: MOLGÓ J. , THESLEFF S.
Published: December 2008

To obtain information about the electric membrane properties of frog motor nerve terminals we examined how depolarizing or hyperpolarizing current pulses of 2–8 ms duration to the preterminal, by electrotonic spread of potential, affected depolarization induced transmitter release. Sodium channels were blocked by tetrodotoxin. Under this condition a hyperpolarizing current pulse produced inhibition of release, followed by poten‐tiation of release. Inhibition lasted more than 100 ms with a time constant of %I50 ms. When, in addition, potassium channels were blocked by 3,4‐diaminopyridine or tetra‐ethylammonium a depolarizing current pulse potentiated transmitter release for a period up to 50 ms. The results imply that inward currents in the nerve terminal are carried mainly by sodium and calcium ions and outward currents by potassium ions while “leak” conductances are negligible. A low “leak” conductance and therefore a high specific membrane resistance facilitates the spread of electrotonic potentials and thereby explains the long‐lasting effects on transmitter release of brief current pulses to the preterminal.
Is muscle structure influenced by genetical or functional factors? A study of three forearm muscles
Authors: FUGL‐MEYER AXEL R. , ERIKSSON ANDERS , SJÖSTRÖM MICHAEL , SÖDERSTRÖM GÖRAN
Published: December 2008

Relative fibre type composition and weights of 3 forearm muscles; the m. extensor carpi radialis longus (ECRL). m. extensor carpi radialis hrevis (ECRB) and the m. bruchioradialis (BR) from both the left and right arm were determined. Fibre type 1 muscle weight of the ECRB. which cocontracts posturally during gripping, was significantly greater in the right than the left forearm. Weights of type 2 fibres in this muscle were. however, similar in the left and right arm. Fibre type weights of both ECRL and BR were also similar in both arms. For all these muscles, intra‐individual co‐variation in relative fibre type occurrence was found. It is proposed that genetic factors may play a role in determining the relative fibre type composition at least as far as the upper extremities are concerned. However, functional demands are also important determining factors for development of muscle structure.
Reflex activation of the sympatho‐adrenal system inhibits the gastrin release caused by electrical vagal stimulation in cats
Authors: UVNÄS‐WALLENSTEN KERSTIN , JÄRHULT JOHANNES
Published: December 2008

The present study on anesthetized cats was performed to investigate how vagally induced gastrin release is influenced by simultaneous activation of the sympatho‐adrenal system. The gastrin concentration in portal blood and in antral perfusates was measured with radioimmunoassay. The vagi were activated electrically and the sympatho‐adrenal system by bilateral clamping of the carotid arteries. It was found that the vagally induced release of gastrin both into the circulation and into the antral lumen, was markedly inhibited (30% of control values) by simultaneous sympathetic activation, both at neutral and at acid intraan‐tral pH. Infusions of adrenaline or noradrenaline did not mimick the effect on gastrin release induced by clamping of the carotid arteries. It is possible that the inhibitory effect of sympathetic activation on stimulated gastrin secretion is mediated via release of an inhibitory peptide. e.g. somatostatin, from the splanchnic nerves.
Complementary role of vasoactive intestinal polypeptide (VIP) and acetylcholine for cat submandibular gland blood flow and secretion
Authors: LUNDBERG JAN M. , ÄNGGÅRD ANDERS , FAHRENKRUG JAN
Published: December 2008

The effects of local intraarterial infusions of VIP, acetylcholine (ACh), substance P. iso‐prenaline and bradykinin on submandibular gland blood flow and salivary secretion were studied in cats. It was found that VIP (lo‐14 to 10‐‐10 mol/min) caused an atropine resistant vasodilation but no salivary secretion. Several hundred fold higher doses of exogenous VIP had to be infused than the amounts of VIP seen in the venous outflow during maximal nerve stimulation at a similar vasodilatory response. ACh infusions (5×10–12 to 5×10‐‐8 mol/min) caused both a muscarinic vasodilation and salivary secretion. ACh was about 100 times less potent than VIP as a vasodilating agent. Both ACh and VIP induced in high doses a vasodilatory response similar to that seen during parasympathetic nerve stimulation at 15 Hz. ACh by itself did in the present doses, however, only induce about 50–60% of the maximal secretory response. Combined infusions of ACh and VIP, had mostly an additive effect on vasodilation. The salivatory volume response to ACh was potentiated by VIP and to a smaller extent also by isoprenaline. This potentiating effect may be due to a direct effect on secretory elements as well as partly to the additional increase in blood flow. Bradykinin was about 1000 times less potent than VIP as a vasodilating agent. Substance P (10‐‐9mol/min) only caused a weak vasodilation. Since there is evidence that ACh and VIP coexist within the same neurons and are both released upon parasympathetic nervous activation, the present findings suggest that the secretory and vasodilatory responses may be caused by an interaction between these two agents.
Effect of age on cardiac index, stroke index and left ventricular ejection fraction at rest and during exercise as studied by radiocardiography
Authors: KUIKKA JYRKI T. , LÅNSIMIES ESKO
Published: December 2008

Radiocardiography was used to measure cardiac output, stroke volume and left ventricular ejection fraction at rest and during muscular exercise in relation with age in 148 healthy subjects (age range: 6–78 years). A clear dependence of these parameters on age was found. The mean annual decrease at rest was 22±9 ml/min/m2 for cardiac index, 0.22±0.04 ml/m2 for stroke index and 0.0017±0.0003 for left ventricular ejection fraction. Male subjects had significantly (p < 0.001) greater cardiac (9±4%) and stroke indices (11±23%) than females. During submaximal exercise cardiac index increased from 3.5±0.7 l/min/m' to 8.1±1.6 l/min/m2 in male subjects (mean age: 32 years) and from 3.1±0.4 l/min/m2 to 7.2±1.2 l/min/ m2 in female subjects (mean age: 29 years). The corresponding increases in stroke index and left ventricular ejection fraction were: from 52±7 ml/m2 to 62±9 ml/m2. from 46±7 ml/m2 to 51±9 ml/m2 and from 0.66±0.08 to 0.79±0.05 and from 0.64±0.10 to 0.72±0.10. In subjects who were 60 years and older the increases of these parameters during exercise were considerably smaller.
Volume regulation of frog skin epithelium
Authors: USSING HANS H.
Published: December 2008

Previous results (MacRobbie & Ussing 1961) in combination with published values for cellular chloride concentration and for intracellular potentials show that the chloride concentration in frog skin epithelium cells is higher than predicted for equilibrium with the inside bathing solution. Both the apical and the basolateral membrane of these cells are normally almost tight to chloride, so that the maintenance of the high chloride concentration requires little work. A basolateral permeability to chloride is, however, activated by cell swelling, and the cells lose KCI. It is now shown that the KCI thus lost cannot be regained neither in the absence of sodium in the inside bath nor in the presence of furosemide. The volume regulation reactions are, however, independent of the composition of the outside bath. It is concluded that the recovery of KCI by the epithelium is due to a basolateral co‐transport of NaCl from medium to cells, combined with return of Na to the medium via the Na‐K pump. The co‐transport mechansism thus restores the high chloride concentration of the cells, but seems to be virtually dormant unless the cells have lost chloride.
Susceptibility of the sympathectomized ear to noise‐induced hearing loss
Authors: BORG ERIK
Published: December 2008

Unilaterally sympathectomiced rats were exposed to 100 dB Leq frequency‐modulated noise for I month. Normotensive as well as spontaneously hypertensive animals (with a blood pressure of above 200 mmHg) were investigated. Auditory sensitivity was determined by auditory brainstem responses to 1/3‐octave filtered sine waves in the frequency range 0.8–20.0 kHz. In addition, a morphological analysis was carried out. It was found that the sympathetic innervation to the inner ear of the rat originated in, or passed through the ipsilateral superior cervical ganglion. Sympathectomy did not alter pre‐exposure hearing thresholds nor influence the size of the noise‐induced hearing loss either in 3 or 11 months old hypertensive rats, or in normotensive rats of 11 months. A slightly smaller loss was seen in the sympathectomized side in young normotensive rats. It was concluded that the sympathetic does not exert a protection of the inner ear against functional disturbances in hypertension, neither during basal metabolic condition nor during extreme conditions, i.e. during noxious noise exposure.
The feedback effect of granulation‐tissue extract on the subcellular level: the degradation of ribosomes
Authors: AHO SIRPA , LEHTINEN PIRJO , KULONEN E.
Published: December 2008

The effects of granulation‐tissue extract and of its purified fractions on the protein synthesis were tested in detached embryonic‐chick tendon cells and granulation‐tissue polysomes. When the subcellular fractions from the incubated tendon cells were compared, the radioactivity in the rough endoplasmic reticulum fractions was decreased, while there was an increase in the lighter subfractions. The glycoproteins purified from the granulation‐tissue extract suppressed the translation of poly(U) as well as that of the mRNA in granulation‐tissue polysomes. The purified fractions degraded rRNA in the ribosomes isolated from granulation tissue.
Changes in myelinated nerve fibres caused by insulating layers
Authors: SOMMER R.‐G. , SCHUMANN H. , KOPPENHOEFER E.
Published: December 2008

Single myelinated nerve fibres of the frog were investigated electron microscopically and electrophysiologically. The following results were obtained. Dissected internodes exhibited small deteriorations only compared to undissected fibres. In the vaseline seal the cross section area of the axoplasm was reduced by a factor of about 3. In the air gap the corresponding figure was about 5. With electrical measurements of up to 2 h the vaseline seal did not affect the axoplasmic resistance of the belonging internode. In corresponding experiments with an air gap. the axoplasmic resistance of the internode doubled after 49±14 min (mean ± S.D.; n=8). Thereafter, the resistance increased rapidly up to about 3000 times normal, depending on the atmospheric humidity. The consequences of these findings for potential clamp experiments are discussed.
Quantitative pharmacological characterization of β‐receptors and two types of α‐receptors mediating sympathomimetic smooth muscle response in the human Fallopian tube at various cyclic stages
Authors: HELM G. , OWMAN CH. , SJÖBERG N.‐O. , WALLES B.
Published: December 2008

The dissociation constants for adrenoceptor‐antagonist complexes (KB) were determined in vitro in circular and longitudinal smooth musculature from the ampullary and isthmic regions of the human Fallopian tube. High extracellular potassium concentrations were used to eliminate the spontaneous contractile activity. Neuronal and extraneuronal amine uptake mechanisms were blocked. The parallel shift of the log dose‐response curves was secured in Arunlakshana‐Schild plots. KB for the β‐receptor, mediating sympathomimetic relaxation, were determined during α‐receptor blockade: the values for propranolol were the same (approximately 10‐‐6 M) in all preparations and at all cyclic stages, as determined from plasma estradiol and progesterone levels. KB for the complex between the a‐receptor (mediating contraction) and phentolamine were determined during preceptor blockade. The values were the same in all types of smooth musculature, but varied with cyclic stage: they were around 7× 10‐‐8 M when plasma estradiol and progesterone were both minimum, and around 2× 10‐‐7 M when these steroid levels were moderate to high, suggesting that the properties of the contractile receptors of the human Fallopian tube are modified during the menstrual cycle.
Lactate accumulation in muscle and blood during submaximal exercise
Authors: TESCH P. A. , DANIELS W. L. , SHARP D. S.
Published: December 2008

Muscle and blood lactate concentration was studied in 10 healthy males during cycling exercise. For each subject the exercise intensity corresponding to a blood lactate concentration of 4 mmol I‐1 (OBLAw) was assessed by a step‐wise increased exercise intensity protocol. In a second series of experiments the same protocol was performed but exercise was terminated at OBLAw and a muscle biopsy for subsequent analysis of lactate concentration was obtained from m. vastus lateralis. Biopsies were also taken at rest for histo‐chemical determination of fiber type composition and capillary supply. The exercise intensity, which corresponded to OBLAw averaged 159(117–216) W, equal to 65 (range 55–84)% of VO2max, and was found to be correlated to capillaries per fiber of the exercising muscle (r=0.83, p>0.01). Muscle lactate concentration averaged 6.9 (range 2.1–12.6) mmol kg‐1 W.W. The change in blood lactate concentration (prior to and I min post exercise) was correlated to muscle lactate concentration (r=0.71, p<0.05). It is concluded that great individual variations in the musclelblood lactate gradient do exist during submaximal steady‐state exercise, performed at a certain blood lactate level.
Lactate in blood, mixed skeletal muscle, and FT or ST fibres during cycle exercise in man
Authors: JACOBS IRA , KAISER PETER
Published: December 2008

The relationship between muscle and blood lactate levels during progressively step‐wise incrementing cycle exercise has been investigated in 10 male subjects. Steps between power outputs during exercise were 50 W and each stage, from loadless pedalling until voluntary exhaustion, lasted 4 min. Blood samples and biopsies (m. vastus lateralis) were taken for lactate determination at each power output beginning with the exercise intensity perceived by the subject as being “rather moderate”. The ratio muscle: blood lactate was greater than one at all power outputs and increased most markedly at the power output closest to that eliciting 4 mmol × I‐1 blood lactate (WOBLA). At WOBLA. blood lactate was positively correlated to muscle lactate concentrations which covaried widely among subjects (mean 8.3. range 4.5–14.4 mmol × kg‐l wet weight). Muscle fibres from the WOBLA biopsy in 6 subjects were dissected out and identified as fast twitch (FT) or slow twitch (ST). No significant difference in lactate concentration was observed between pools of FT or ST fibres.
Short‐range elasticity after tetanic stimulation in single muscle fibres of the frog
Authors: HAUGEN P.
Published: December 2008

The time course of the stiffness during the relaxation period following tetanic stimulation was studied in isolated single muscle fibres of the frog. The stiffness was measured by subjecting the fibres to a sudden stretch at constant velocity from an initial sarcomere length of 2.2 μm, and related to the tension carried by the muscle fibre immediately before the stretch. Both stiffness and tension fell close to the resting level during the first second (4°C) after the end of stimulation. While stiffness and tension fell proportionally during the phase of almost exponential decline in tension following the shoulder in the tension recording, the relative drop in stiffness was less than the relative drop in tension during the preceding phase of almost linear decline in tension corresponding to the first 300–400 ms after the end of stimulation.
Neurotensin‐induced increase in intestinal blood flow in the anesthetized rat
Authors: ONARHEIM J. , HELLE K. B. , JØRGENSEN G.
Published: December 2008

Cardiac output (CO) and blood flow to major organs were investigated in pentobarbital‐anesthetized rats using H5Sr and 141Celabelled mierospheres (MS) of 15 mUm diameter injected into the left ventricle. Changes in organ blood flow and CO were measured after intraventricular dextran (3.4 μmol/kg/min) and intravenous neurotensin (NT) at two differ ent rates, 2.5 nmol/kg/min and 0.125 nmol/kg/min. Dextran, known to give anaphylactoid response in rats, reduced the mean arterial pressure (MAP) from 118±17 to 55±8 mmHg (p<0.001) concomitant with a 56% decline in CO and significant decreases in blood flow to most organs. At 2.5 nmol/kg/min, NT caused a pattern of changes in MAP. CO and organ blood flow similar to that obtained with dextran, and thus consistent with an indirect response via mast cell stimulation. NT injected at 0.125 nmol/kg/min resulted in a significant increase (30%) in blood flow to the small intestine (p<0.01) without changes in MAP or CO. Vascular resistance decreased by 30% in the small intestine (p<0.01) and by 20% in the large intestine (p<0.05). The results show that circulating NT, at concentrations below those eliciting hypotension, enhances intestinal blood flow without significant changes in other organs.
Countercurrent exchange of progesterone and antipyrine between human utero‐ovarian vessels, and of antipyrine between the femoral vessels in the cat
Authors: BENDZ A. , LUNDGREN O. , HAMBERGER L.
Published: December 2008

The utero‐ovarian vein and ovarian artery in surgical specimens were cannulated and perfused in a countercurrent manner with isotonic, buffered solutions, fortified on the venous side with progesterone or radiolabelled methylantipyrine. Both substances were gradually transferred from the vein into the artery in the majority of the experiments while albumin was not exchanged. The results point to the existence of a countercurrent exchange mechanism in the human ovarian pedicle. Hardly detectable amounts of methylantipyrine were transferred from femoral vein to artery in the cat.
Atropine‐sensitive gastric excitation by stimulation of thoracic dorsal roots—antidromic activation of afferents?
Authors: DELBRO D. , ANDERSSON S. A.
Published: December 2008

In chloralosed cats. usually with ligated adrenals and paralysed with gallamine, the thoracic dorsal roots were electrically stimulated and gastric motor responses were recorded. Thoracic dorsal root stimulation regularly elicited gastric contractions after pretreatment with guanethidine and/or hexamethonium which were readily blocked by atropine. It was established that these gastric motor responses were due to peripheral stimulation of the dorsal root and not to spread to the ventral roots. Together with other results (Delbro & Lisander 1980) the findings suggest an antidromic activation of thin afferent fibres with excitatory collaterals to intramural cholinergic neurons which convey the gastric contractions.
Functions of adrenergic and cholinergic nerves in canine effectors of seminal emission
Authors: ARVER STEFAN , SJÖSTRAND NILS O.
Published: December 2008

Spontaneous activity responses to acetylcholine (ACh), adrenaline (A), noradrenaline (NA) and barium chloride as well as the effects of various autonomic drugs on effects of field stimulation of nerves and muscle cells of isolated pieces or strips of cauda epididymidis, vas deferens, ampulla ductus deferentis and prostate of dog were studied. The main results and conclusions are: the muscles show little spontaneous activity but rhythmicity can easily be produced by e. g. stimulating agonists. The muscles are contracted by α‐adrenoceptor stimulants. ACh has usually no or a very weak contractile effect in high concentrations. Muscles of young dogs are more sensitive to ACh. The excitatory innervation of the muscles is adrenergic and completely blocked by adrenergic neuron blockers as well as α‐adrenoceptor blocking drugs. Stimulation of adrenergic nerves leads to maximum response already at low frequencies (4–6 Hz). This response is very similar to that provoked by a supramaximal dose of NA. Scopolamine enhances neurogenic contractile effects while physostigmine suppresses them. Hence cholinergic nerves may act by muscarinic prejunctional inhibition of the excitatory adrenergic neurotransmission rather than act directly upon the smooth muscle cells. Since secretory cells receive cholinergic innervation prejunctional inhibition of the adrenergic myomotor nerves may be of functional significance in at least the long copulatory events of the dog.
Electrophysiological evidence of degeneration activity in the parotid gland of the rat
Authors: THESLEFF PETER
Published: December 2008

In the parotid gland of the rat intracellular recordings were made 13–30 hours after section of the auriculo‐temporal nerve or excision of the superior cervical ganglion. Shortlasting membrane potential changes (hyperpolarisation or depolarisation) and resistance decreases, much larger and more frequent than in the control gland, were observed. The degeneration activity after parasympathectomy was blocked by atropine, whereas the sympathetic degeneration activity was blocked by the α‐blocker dihydroergotamine. The electrical activity is thus believed to be due to release of neurotransmitter from degenerating nerve fibres; β‐blockers and tetrodotoxin did not significantly affect the activity.
Spinal evoked potentials evaluated with two relevant electrode types
Authors: SIIVOLA J. , JÄRVILEHTO M.
Published: December 2008

The spinal evoked potentials (SEPs) were recorded at the level of the 7th lumbar segment in five cats by stimulating the popliteal nerve separately on both sides. The recordings were performed both with silver‐silver chloride cup electrodes and stainless steel needle electrodes. The shapes and latencies of the responses were highly similar, when comparing the responses recorded with the two electrode types. These similarities are explained by similar recording properties of both electrode types as shown by means of transfer function: attenuation and phase curves for both electrode types are highly similar in the bandpass used in the present study. It is concluded that the properties of stainless steel needle electrodes are highly correspondent with the conventional silver‐silver chloride electrodes when somatosensory evoked responses are recorded.
Effect of vagotomy on gastric acid secretion in the rat
Authors: HÅKANSON R. , HEDENBRO J. , LIEDBERG G. , VALLGREN S.
Published: December 2008

The effects of pentagastrin, histamine or feeding on gastric acid secretion were studied in conscious rats with total gastric by‐pass, achieved by transection of the cardia and pylorus, followed by an oesophago‐duodenostomy. After closure of the cardia, the by‐passed stomach was connected to the small intestine through a Roux‐en‐Y loop. A chronic gastric fistula was fitted into the rumen. Basal acid output was low in chronically vagotomized rats, being 6% of that in the innervated animals. A clear‐cut stimulation was observed after both pentagastrin and histamine in innervated as well as denervated rats, although the maximal acid output in the denervated group was less than 10% of that in the innervated group. In previous studies on acid secretion in vagotomized rats with chronic gastric fistulas, neither basal nor stimulated acid secretion could be detected. Apparently, by‐passing the stomach eliminates sources of error associated with the conventional gastric fistula technique (for instance, neutralization of acid gastric juice by swallowed saliva or regurgitated duodenal juice). Nonetheless, the greatly reduced acid output following vagotomy indicates that normal basal as well as normal stimulated acid secretion is dependent upon an intact vagus. Pentagastrin‐ and histamine‐stimulated acid secretion was blocked by atropine and cimetidine in both the innervated and denervated rats. Feeding caused a significant inhibition of acid secretion in the by‐passed, innervated stomach. In the denervated stomach feeding was without effect. The mechanism behind the postprandial inhibition of acid secretion in the innervated stomach is obscure. Direct vagal inhibition as well as humoral substances, liberated by vagal stimulation or by the presence of food in the intestine, may be responsible.