摘要:

Altered shape and size of red blood cells in obese hyperglycaemic mice.Acta Physiol Scand130, 535–543. Received 31 October 1986, accepted 2 March 1987. ISSN 0001–6772. Department of Histology and Cell Biology, University of Umeå, Sweden.Red blood cells (RBCs) from hyperglycaemicob/ob‐mice, normoglycaemic controls, and a healthy man were sucked into a narrow capillary, photographed and measured. Mouse RBCs had a smaller diameter than human ones. Although of normal diameter, theob/ob‐mouseRBCs exhibited increased area and volume, and more frequently than control RBCs had a minimum cylindrical diameter greater that 3 μm. Cross‐sectional profiles with minimum bending resistance were computed for RBCs of mean area and volume. The diameters of these theoretical profiles agreed closely with those empirically observed, in both mice and man. The profile ofob/ob‐mouseRBCs predicted a greater resistance to corpuscle bending than the control profile. It is concluded that changes in shape and size explain the decreased filtrability of diabeticob/ob‐mouseRBCs. The results also suggest that the actually occuring smooth biconcavity is in general the RBC shape with maxi

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1987.tb08174.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

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 extracellula

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1987.tb08175.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

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 ± 5.4us. 100.1±1.6 mmHg;P0.05), HR (118.1±4.4us. 87.8 ± 3.7 beats min‐1;P0.001) and PRA (3.0±0.8us. 0.9 ± 0.2 ng A1 m‐1h‐1;P0.05). 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 no

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1987.tb08176.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Role of dopamine2‐receptors in mediating renal vascular response to low dose dopamine infusion in the rat.Acta Physiol Scand130, 563–569. Received 6 November 1986, accepted 15 March 1987. ISSN 0001–6772. Department of Developmental Physiology, Karolinska Institute, St Göran's Children's Hospital, Stockholm, Sweden.The effects of the interaction of dopamine (DA) and the DA2‐receptors on regional blood flows and cardiac output have been studied in the rat. By means of the microsphere technique the blood flow (BF) and vascular resistance (VR) were determined in the kidney, duodenum, spleen, liver, and lung during infusion of DA in the absence and presence of selective DA2‐receptor blockade with S‐Sulpiride (S‐SP), and during infusion of a selective DA2‐receptor agonist (LY‐171555, LY). In order to evaluate the role of the presynaptic DA2‐receptor, the experiments were performed without α‐ and β‐adrenergic blockade. Dopamine was given in such low doses that stimulation of the adrenergic receptors should be negligible. Dopamine, LY and DA + S‐SP did not significantly influence BF and VR in the spleen, liver and lung. Dopamine significantly increased BF and decreased VR in the kidney and the duodenum; LY significantly increased BF in the the kidney but not in the duodenum and decreased VR in both the kidney and the duodenum. In the presence of selective DA,‐receptor blockade, DA did not significantly influence BF or VR in the kidney but in the duodenum BF increased and VR decreased to the same extent as in the absence of blockade. In conclusion; the kidney and the intestine are more abundantly supplied with vascular DA‐receptors than other organs. In the kidney the interaction between DA and the DA2‐receptors significantly contributes the the DA‐induced vasodilation. The interaction between DA and the DA2‐receptors is of less importance for the DA

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1987.tb08177.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Effect of L‐Dopa, dopamine, dihydroxyphenyl acetic acid and homovanillic acid on Na, K‐ATPase activity in rat proximal tubule segments.Acta Physiol Scand130, 571–574. Received 6 November 1986, accepted 16 February 1987. ISSN 0001–6772. Department of Developmental Physiology, St Görans Children's Hospital, Stockholm, Sweden.We have recently demonstrated that dopamine (DA) inhibits Na, K‐ATPase in single proximal tubule (PCT) segments dissected from previously collagenase perfused rat kidney. The aim of the present study was to ascertain whether this effect was directly mediated by DA or if DA was the precursor of an inhibitor. When PCT segments were incubated with I.‐Dopa, Na,K‐ATPase was significantly lower than in vehicle incubated tubules. Inhibition of dopa decarboxylase abolished the effect of L‐Dopaon Na,K‐ATPase activity. The metabolites of DA, 3, 4‐dihydroxyphenyl acetic acid (DPAC) and homovanillic acid (HVA) both inhibited Na,K‐ATPase activity in doses higher than 10‐‐6M. Both HVA and DPAC 10‐‐4M caused approximately 35% inhibition. Dopamine inhibited Na,K‐ATPase activity even in a dose as low as 10‐‐7M. Maximal inhibition (>60%) was found with DA‐5M. Na,K‐ATPase activity was significantly lower in tubules exposed to DA 10‐‐4and 10‐‐5M than in tubules exposed to DPAC or HVA 10‐‐4and 10‐‐5m. Dopamine produced in proximal tubule cells from L‐Dopa, is an active inhibitor of the Na,K‐pump in these cells. The DA m

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1987.tb08178.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Interaction of changes in the third ventricular CSF tonicity, central and systemic AVP concentrations and water intake.Acta Physiol Scand130, 575–583. Received 23 January 1987, accepted 8 March 1987. ISSN 0001–6772. Max‐Planck‐Institut für physiologische und klinische Forschung, W. G. Kerckhoff‐Institut, Bad Nauheim, FRG and Department of Physiology I, Karolinska Institute, Stockholm, Sweden.Arginine vasopressin (AVP) is assumed to be involved as a central transmitter or modulator in the control of autonomic functions including thirst. In conscious dogs AVP concentration in cerebrospinal fluid (CSF) from the anterior part of the third ventricle (A3V) was analysed before and after local elevation of CSF osmolality by intracerebroventricular (i.c.v.) infusion of 0.35 m NaCl and after i.c.v. AVP infusion at 46 and 138 fmol ml‐1for 10 min. In addition, the effects of these i.c.v. infusions on water intake, plasma AVP concentration and blood pressure were investigated. In euhydrated dogs 0.35 M NaCl i.c.v. did not alter AVP concentration in the CSF during the subsequent 2 h. In contrast, plasma AVP concentration had increased significantly from 3.4±0.3 (control) to 6.4 ± 0.7 and 4.7 ± 0.3 fmol ml‐1, 4 and 16 min, respectively, after the hypertonic stimulus. Drinking was stimulated with an average water intake of 14.5 ± 3.7 ml kg‐1body wt. However, AVP infusion into the A3V did not elicit water intake despite increases of AVP concentration in the A3V by factors up to 40 above control. The same animals responded with spontaneous drinking to 0.35 m NaCl i.c.v. administered 160 min after the end of AVP infusions. Exogenously administered AVP disappeared from the A3V with a time constant of 13.8 min. The results do not support the view that AVP in the A3V CSFper s

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1987.tb08179.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Renal and hormonal responses to atrial natriuretic peptide infusions in goats on high and low sodium intake.Acta Physiol Scand130, 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 (Iμg 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‐ind

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1987.tb08180.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Comparison of atriopeptins II and III, VIP andβ2‐‐adrenoceptor‐evoked relaxations in the two layers of smooth muscle in the rat portal vein.Acta Physiol Stand130, 593–599. Received II November 1986, Accepted 26 February 1987. ISSN 0001–6772. Department of Physiology, University of Bergen, Norway.The relative importance of vascular relaxations induced by atriopeptins (AP), theβ‐adrenoceptor agonist isoprenaline and of the neuropeptide VIP was studiedin uitroon circular and longitudinal preparations of the rat portal vein. Two members of the rat atriopeptins (AP II and III) were equipotent with respect to relaxation of the spontaneously contracting outer, longitudinal layer and of theα1‐‐contracted inner, circular layer. The potency for AP II was about 13 times lower in the inner (pD2= 7.48±0.73,n= 6) than in the outer layer (pD2= 8.60 ±0.34,n =6). No significant difference was apparent between the intrinsic activities for AP II in the two layers. The potencies for AP II were for both layers higher than those for VIP while the intrinsic activities for AP II were significantly lower than for VIP and for the reference agonist, isoprenaline in both layers. Atriopeptin II was equally efficient in relaxing the K+‐depolarized anda1‐‐contracted longitudinal segments. Neither theβ‐antagonist, propranolol nor the guanylate cyclase inhibitor, methylene blue, modified the potency or the intrinsic activity of AP II. These results suggest that concentrations of circulating atriopeptins above 10 nM may contribute to reduction of vascular tone by the methylene blue insensitive receptors for AP II and III in the

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1987.tb08181.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Comparison of VIP andβ2‐‐adrenoceptor‐induced relaxations in the circular and longitudinal smooth muscle layers of the rat portal vein.Acta Physiol Scand130, 601–607. Received I I November 1986, accepted 26 February 1987. ISSN 00014772. Department of Physiology, University of Bergen, Norwegian Defence Research Establishment, Kjeller, Norway.The relative importance of VIP in reduction of vascular tone was studied in circular and longitudinal preparations of the VIP‐innervated rat portal vein. Exogenous VIP inhibited the methoxamine‐evoked contractures in the atropine‐blocked preparations with a lower potency in the inner, circular (pD2= 6.4±0.5,n= 6) than in the outer, longitudinal layer (pD2= 7.7 ± 0.1, n = 6). VIP was also a less efficient relaxant (intrinsic activity (a) = 0.60 ±0.16, n = 6) of the inner than of the outer layer (a= I. 00). The selective (salbutamol) and the non‐selective (isoproterenol)β2‐‐agonists completely relaxed the methoxamine contractures in both layers and the potency (isoproterenol) was higher in the inner (pD2= 6.39 ± 0.32, n = 6) than in the outer layer (pD2= 5.67 ±0.34,n= 6). Plasma from the portal‐mesenteric vein of anaesthetized, fasting rats contained 0.036 nM VIP (median,n= 17). that is, several orders of magnitude lower than the range of VIP concentrations relaxing the methoxamine contracted vein preparations via VIP receptors of the apamin‐blockable category. The results support the hypothesis thata1‐‐adrenoceptor‐induced contractions in the circular layer are predominately relaxed viaβ2‐‐adrenoceptors while relaxation of the outer layer may occur via VIP receptors, probably activ

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1987.tb08182.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Binding and degradation of vasoactive intestinal peptide in prolactin‐producing cultured rat pituitary tumour cells (GH4C1).Acta Physiol Scand130, 609–618. Received 17 October 1986, accepted 2 March 1987. ISSN 0001–6772. Hormone Laboratory, Aker Hospital, Oslo, Norwegian Defence Research Institute, Division for Environmental Toxicology, Kjeller, and Institute of Medical Biochemistry, University of Oslo, Norway.Vasoactive intestinal peptide (VIP) stimulates prolactin (PRL) secretion from cultured rat pituitary cells (GH cells) (Bjeroet al. 1984). This study demonstrates the presence of specific receptors for125I‐VIP on the GH4C1cells. Specific binding was rapid and biphasic giving a transient plateau lasting from 7 to 30 min. Thereafter specific binding declined to about one‐third after 90 min. This coincided with enhanced degradation of125I‐VIP. The degradation was mainly cell‐mediated and only partly receptor dependent. Trichloroacetic acid precipitation and absorption chromatography indicated that the degradation products were either125I‐and/or small labelled peptide fragments. Bioassay, RIA and rebinding studies also demonstrated degradation of VIP. Pretreatment of GH4C1cells with trypsin decreased the rate of degradation of125I‐VIP, but also reduced the amount of specific binding. Scatchard analysis of binding data indicated the existence of two independent classes of receptors, one with Kd= 2.2 nM andBmax= 15 fmol per 106cells and another with Kd= 180nM andBmax= 550 fmol per 106cells. The IC50for VIP, PHI and secretin were 4, 5 and 500 nM, respectively. We conclude that the high affinity receptor is the most probable mediator of VIP on PRL secretion. The effect of VIP and PHI on PRL secretion in GH4C1cells is mediated through on

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1987.tb08183.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY