Effect of splanchnicotomy on the renal excretion of uric acid in anaesthetzed dogs

Summary The renal excretion of uric acid was examined during acute i.v. urate (Ua) loading on unilaterally splanchnicotomized (renal denervation) anaesthetize mongrel dogs. Glomerular filtration rate (GFR) in general was not different in innervated and denervated kidneys, whereas urine flow (V) and urinary excretion of sodium (U_NaV) on the splanchnicotomized side were significantly increased at any plasma concentration of Ua. The excretion (U_UaV) and tubular transport (T_Ua) of urate calculated for unit GFR were considerably increased and depressed, respectively, at normal plasma Ua level and during minor urate loading (plasma concentration up to 4.7 mg%). Above this plasma level, i.e. up to 24.6 mg%, no difference in net urate reabsorption between intact and sympathectomized organs was found. It is suggested that both reabsorption and secretion of Ua in denervated kidneys are diminished.     

Effect of splanchnicotomy on the renal excretion of para-aminohippuric acid in the anaesthetized dog

Summary Renal excretion of para-aminohippuric acid (PAH) was studied during PAH loading on unilaterally splanchnicotomized (denervated) anaesthetized dogs. Urine flow, sodium excretion of denervated kidneys were significantly increased. Below a plasma concentration of 20 mg% there were no differences between intact and denervated kidneys in urinary excretion and in calculated tubular transport of PAH. However, maximum secretion rate on the splanchnicotomized side was significantly decreased (innervated: 34.8, denervated: 25.2 mg/100 ml GFR, respectively). Although both Na reabsorption and PAH secretion are impaired by denervation, the exact mechanism of action of renal sympathectomy is not elucidated as yet.     

Supersensitivity of the renal tubule to catecholamines in the chronically denervated canine kidney

Experiments were performed on anesthetized dogs to study whether or not renal tubules of the chronically denervated kidney show supersensitivity toward circulating catecholamines. In one kidney the influence of plasma catecholamines was inhibited by intrarenal administration of the alpha adrenergic receptor blocker phenoxybenzamine (POB, 2 g/min), and renal parameters of the infused kidney were compared to those of the contralateral noninfused organ. Before POB infusion urine flow (V), urinary sodium and potassium excretion (U_NaV, U_KV) as well as clearance of inulin and PAH (GFR, C_PAH) were similar in infused and contralateral kidneys in all the groups studied. In dogs (n=8) with two innervated kidneys POB infusion elevated V and U_NaV by 53±13% and 102±34% (p<0.05). In dogs (n=8) with acute bilateral renal denervation POB administration failed to alter any of the measured parameters. In contrast, V and U_NaV from chronically denervated kidneys (n=7) were increased after POB infusion by 40±9% and 103±34% (p<0.05). Glomerular filtration rate, C_PAH and U_KV were not changed by alpha adrenoceptor blockade in any of the groups. In an additional group of animals (n=8) acute unilateral renal denervation increased V and U_NaV to a significantly higher extent (by 282±85% and 330±106%) than POB administration did in the innervated kidney and elevated U_KV (44±10%), too. It is concluded that supersensitivity to catecholamines developed in renal tubules of the chronically denervated dog kidney and, in consequence, circulating catecholamines at elevated plasma levels caused by surgery were capable of increasing tubular reabsorption of sodium and water.     

GM1-gangliosidosis: Chromosome 3 assignment of theβ-galactosidase-A gene (β GAL A )

The structural gene (GAL_A) coding for lysosomal -galactosidase- A (EC 3.2.1.23) has been assigned to human chromosome 3 using man-mouse somatic cell hybrids. Human -galactosidase-A was identified in cell hybrids with a species-specific antiserum to human liver -galactosidase-A. The antiserum precipitates -galactosidase-A from human tissues, cultured cells, and cell hybrids, and recognizes cross-reacting material from a patient with G_M1 gangliosidosis. We have analyzed 90 primary man-mouse hybrids derived from 12 separate fusion experiments utilizing cells from 9 individuals. Enzyme segregation analysis excluded all chromosomes for GAL_A assignment except chromosome 3. Concordant segregation of chromosomes and enzymes in 16 cell hybrids demonstrated assignment of GAL_A to chromosome 3; all other chromosomes were excluded. The evidence suggests that G_M1 gangliosidosis is a consequence of mutation at this GAL_A locus on chromosome 3.     

Heparin uncouples the muscarinic receptors from GK protein in the atrial cell membrane of the guinea-pig heart

The effects of heparin on activation of the G protein-gated muscarinic K⁺ channel were examined in atrial cells of guinea-pig heart. The inside-out patch clamp technique was used. The pipette solution contained 1.1 M acetylcholine (ACh). In the inside-out patches, intracellular GTP activated the muscarinic K⁺ channel. When heparin (0.05–5 units/ml) was further added to the intracellular side of the patch membrane, the channel openings were depressed in a concentration-dependent fashion. The effects of heparin were reversible after wash-out. Heparin did not affect GTP-S-induced activation of the K⁺ channel. Therefore, it is suggested that heparin may uncouple the muscarinic receptors from G_K protein in the cardiac atrial cell membrane.     

Renal sodium reabsorption and oxygen consumption after unilateral splanchnicotomy in the dog

Summary Experiments were carried out on pentobarbital-anaesthetized dogs previously subjected to unilateral splanchnicotomy. Renal blood flow (RBF), glomerular filtration rate (GFR), tubular reabsorption of sodium (TRF_Na), and oxygen consumption (Q _{O 2}) were determined in normal state, following isotonic volume expansion and during furosemide administration (0.5–1.5 mg/kg bw.). Denervation diuresis and natriuresis occurred under all experimental conditions. TRF_Na/Q _{O 2} was 31.4 mEq/mMol for intact and 27.7 mEq/mMol for denervated kidneys in the normal and isotonic volume expanded dogs. These values decreased significantly to 16.8 mEq/mMol and 18.3 mEq/mMol, respectively, upon furosemide loading. No difference between intact and denervated kidneys was observed in either group. TRF_Na, RBF, and GFR were significantly correlated toQ _{O 2} with no difference between intact and splanchnicotomized sides. An inhibitory effect of renal denervation on active sodium transport in the proximal tubule is suggested.     

Filtration and reabsorption of the denervated kidney under normal conditions and under the influence of various neurotropic substances

Summary Chronic experiments on 8 dogs were made to study the effect of renal denervation on spontaneous and water diuresis, filtration and reabsorption, chloride excretion and renal blood flow; the observations were made during the first month after the operation. From the 10–12th day after denervation onwards, filtration and reabsorption in the denervated kidney were greater than in the intact one; there were no material changes of diuresis or chloride excretion. The intact and denervated kidneys reacted in the same way to novocain and aminasine (chlorpromasine) administration.(Presented by Active Member AMN SSSR V. V. Parin) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 53, No. 5, pp. 84–89, May, 1962     

Effect of 1-(4-amino-2-methyl-5-pyrimidil)methyl-3-(2-chloroethyl)3-nitrosourea hydrochloride (ACNU) on glioma cells: ultrastructural observation using cell-cycle-specific cell sorting by flow cytometry

To assess the effect of 1-(4-amino-2-methyl-5-pyrimidil)methyl-3-(2-chloroethyl)3-nitrosourea hydrochloride (ACNU) on human glioma, we performed cell-cycle-specific cell sorting followed by electron microscopic observation. Cells sorted from an accumulated SG₂M peak caused by treatment with 10g/ml ACNU showed a number of cells similar to S-phase cells in the untreated samples, having no microvilli. Cell organelles were intact, and no ultrastructural evidence for cell injury was observed. In contrast, many cells sorted from nonstagnated G₀G₁ and SG₂M peaks in the samples treated with 100g/ml ACNU showed mitochondrial swelling that suggested cell necrosis.     

Renal tubular reabsorption of taurine,γ-aminobutyric acid (GABA) andβ-alanine studied by continuous microperfusion

Summary Renal tubular reabsorption of taurine, -aminobutyric acid (GABA), and -alanine was studied in vivo et situ by continuous microperfusion of single proximal tubules of the rat. In each case, reabsorption was much slower than that for other amino acids that have been studied. With a concentration of 0.1 mmol/l in initial perfusate, about 60% of initial load was reabsorbed over perfusion distance of 3 mm. Taurine reabsorption saturated with only 2.17 mmol/l in initial perfusate. Assuming simple two-parameter kinetics, upper limits for K _m of 0.54 mmol/l and forV _max of 0.59 pmol·cm^–1·s^–1 for tubular reabsorption of taurine were estimated. High (20 mmol/l) concentrations of taurine or -alanine in perfusate completely inhibited GABA reabsorption, butl-phenylalanine (20 mmol/l) had no significant effect. The results indicate that the three amino acids are reabsorbed slowly from the proximal tubule by what may be a common transport system. This system appears to have a high affinity but low capacity and to be different from other known renal tubular transport systems for amino acids.Supported by National Science Foundation Research Grant No. PCM 75-09918 and by grant No. 1740 of the Austrian Fonds zur Förderung der Wissenschaftlichen Forschung.     

Effect of dietary sodium content on renal handling of lithium

Previous studies have shown that the clearance of lithium (C_Li) is a quantitative measure of the delivery of tubular fluid to Henle's loop in rats given food with an ordinary or high sodium content but not in rats given food with a low sodium content, because under these circumstances lithium is also reabsorbed to some extent in the distal nephron segment. The present study examines C_Li, C_Na and urine flow in diabetes insipidus rats at various dietary sodium contents. The results showed that C_Li was 120 l/min/100 g b.w. when no distal reabsorption took place at a dietary sodium content of 300 mmol/kg. At a dietary sodium content of 5 mmol/kg the calculated distal lithium reabsorption reduced C_Li by 55 l/min/100 g b.w.; at 25 mmol/kg distal reabsorption was reduced to half this value; at 50 mmol/kg distal reabsorption was slight and barely significant, and at 75–300 mmol/kg there was no distal reabsorption of lithium. It is concluded that C_Li can be used as a quantitative measure of the delivery of tubular fluid to the loop of Henle at dietary sodium contents higher than 50–75 mmol/kg in the rat.     

The effect of phosphatase inhibitors and agents increasing cyclic-AMP-dependent phosphorylation on calcium channel currents in cultured rat dorsal root ganglion neurones: interaction with the effect of G protein activation

Ca²⁺ channel currents have been recorded in cultured rat dorsal root ganglion neurones. The amplitude of I _Ba(GTPS), recorded in the presence of GTP[S] (200 M) in the patch pipette solution, is enhanced by external application of forskolin (10 M), and there is an increase in the proportion of the rapidly activating component of the current. When forskolin (1 M) is present in the bathing solution at the start of recording, or when 8-bromocyclic AMP (100 M) is present in the patch pipette solution, the amplitude and rate of activation of I _Ba(GTPS) are also increased compared to control I _Ba(GTPS). The effect is mimicked by internal application of a 5 M solution of a phosphopeptide fragment of inhibitor 1 (I1PP), which inhibits phosphatase 1. The enhancement of I _Ba(GTPS) caused by I1PP is not additive with that due to forskolin. Furthermore, the enhancement due to I1PP is reversibly lost when the holding potential is shifted from –80 mV to –30 mV, as was the enhancement due to forskolin and 8-bromocyclic AMP. I1PP also produced a less marked stimulation of the control Ca²⁺ channel current in the absence of G protein activation. The results suggest that phosphorylation regulates the interaction between calcium channels and G proteins in these neurones, and that phosphatase 1 is tonically active to dephosphorylate the relevant protein(s).     

Expression of parathyroid hormone receptors in MDCK and LLC-PK1 cells

Parathyroid hormone (PTH) inhibits renal proximal tubular phosphate (P_i) and bicarbonate reabsorption by regulating the activity of apical Na/P_i cotransport and Na/H exchange. Two renal epithelial cell lines [proximal tubular, LLC-PK₁; distal tubular, Madin-Darby canine kidney, (MDCK) cells] were stably transfected with complementary deoxyribonucleic acids (cDNAs) encoding a cloned PTH receptor in order to examine the polarity of transfected receptor function and whether or not intrinsic P_i transport is regulated by the transfected PTH receptor. The receptors are functionally coupled to the stimulation of adenosine 35 cyclic monophosphate (cAMP) production at both cell surfaces in LLC-PK₁ cells, whereas this response is primarily limited to the basolateral surface in MDCK cells. Immunocytochemistry suggests an apical and basolateral localization of the transfected PTH receptor in LLC-PK₁ cells and only a basolateral localization in MDCK cells. PTH activation of the transfected receptors is not coupled to the regulation of intrinsic P_i transport in either LLC-PK₁ or MDCK cells.     

Modulation of the effect of arginine-vasopressin on water and ion transport in the newt early distal tubule and frog urinary bladder by V1-antagonists

In the early distal tubule of the newtTriturus vulgaris L., 1 nM arginine-vasopressin (AVP) increased water reabsorption; the fractional reabsorption of Na⁺ was elevated from 46.2±6.9% to 67.8±3.9% (P<0.001), of Cl^– from 52.7±6.7% to 73.1±3.5% (P<0.001), of Mg²⁺ from 48.0±7.7% to 71.7±6.3% (P<0.001). When V₁-receptors were blocked by 1 nM peptide V₁-antagonist [1-(-mercapto-,-cyclopentamethylene propionic acid), 2-(O-methyl) Tyr]-[Arg⁸]vasopressin, 1 nM AVP increased the fractional reabsorption of fluid by 8.9% of Na⁺ by 10.7% and of Cl^– by 11.2%, as compared with the effect of AVP alone. The fractional reabsorption of Ca²⁺ after addition of AVP did not differ from control; when V₁-receptors were blocked in the presence of AVP, the fractional reabsorption of Ca²⁺ was increased by AVP. The V₁-receptor block in the presence of AVP did not change the fractional reabsorption of Mg²⁺. Experiments on the urinary bladder of the frogRana temporaria L. showed that 1 nM SR 49059, a non-peptide antagonist of V_1a-receptors, like the peptide V₁antagonist, enhanced the AVP effect by 29%. Inhibition of protein kinase C activity by calphostin C (1 nM) mimicked the effect of V₁-antagonists; the AVP hydroosmotic effect was increased by 60%. The results obtained indicate that V₁-receptors modulate the effects of V₂-receptor activation: their block is accompanied by an enhancement of the AVP hydroosmotic effect in the frog urinary bladder and by an increase of Na⁺ and Cl^– reabsorption in the newt early distal tubule. The enhancement of the AVP effect owing to the V₁-receptor activation seems to be mediated by a decrease in protein kinase C activity.     

Six novel UDP-glucuronosyltransferase (UGT1A3) polymorphisms with varying activity

Human UDP-glucuronosyltransferase (UGT) is a part of a major excretion pathway for endobiotics and xenobiotics. The UGT family of genes is highly polymorphic, and our aim is to describe novel polymorphisms at the UGT1A3 locus and determine how they alter substrate metabolism and drug reactions. One hundred healthy Japanese adults volunteered for the present study. We sequenced PCR-amplified fragments of the gene directly, and calculated the frequency of the genetic variations detected. To measure variant enzyme activity, we constructed five expression models and used estrone as the substrate in the assays. We identified six novel single nucleotide polymorphisms (SNPs). Of these, four caused amino acid substitutions (17AG: Q6R, 31TC: W11R, 133CT: R45W, and 140TC: V47A) and the remaining two were silent (81GA: E27E and 447AG: A159A). We found five types of alleles having differing SNP combinations: wild type (frequency=0.61), W11R-E27E-A159A (0.10), Q6A-W11R-E27E-A159A (0.055), W11R-E27E-V47A-A159A (0.125), and R45W (0.11). Expression studies found that the variants changed the enzyme efficiencies (K _m/V _max) to 121% of the wild type for W11R, 86% for Q6R-W11R, 369% for W11R-V47A, and 70% for R45W. Several UGT 1A3 polymorphisms exist in the Japanese population, having different levels of activity. These polymorphisms are capable of affecting the steady state levels of estrogens, and may increase sensitivity to adverse drug effects.The accession numbers of new nucleotides: AB120359, AB120360, AB120361, AB120362.     

Mechanism of inorganic phosphate diuresis secondary to saline infusions in the rat

Summary Clearance studies have been performed in rats undergoing saline diuresis. Saline infusion was increased from 0.15 to 0.5 ml/min during each experiment in order to examine the effect of extracellular fluid volume expansion on the excretion of sodium, inorganic phosphate, and calcium in normal and parathyroidectomized animals.In normal animals excretion of sodium, inorganic phosphate, and calcium increased significantly (P<0.001) from 13.7 to 56.6 Eq/min, from 0.69 to 1.34 M/min, and from 0.54 to 0.87 Eq/min, respectively, under these conditions. Fractional excretion of sodium rose from 3.8 to 13.3%, fractional excretion of inorganic phosphate from 13.8 to 27.2%, when infusion rate was elevated from 0.15 to 0.5 ml/min.In parathyroidectomized animals excretion rates of sodium and calcium were similar. In contrast, after parathyroidectomy inorganic phosphate excretion was almost abolished, being 0.0058 and 0.0121 M/min or 0.2 and 0.3% of filtered inorganic phosphate at the lower and the higher infusion rate, respectively.It is concluded, that the presence of intact parathyroids is a prerequisite for the mediation of the normal phosphaturic response secondary to saline infusions.This work was supported in part by a grant from the Deutsche Forschungsgemeinschaft.     

Thermogenesis in brown adipose tissue with age: Post-receptor activation by forskolin

₃-Adrenergic-stimulated thermogenesis in brown adipose tissue (BAT) is diminished with age. ₃-Adrenergic receptors are positively coupled to adenylyl cyclase in BAT. To determine whether thermogenesis, in response to direct activation of adenylyl cyclase, is also impaired with age, we examined whole body oxygen consumption, mitochondrial guanosine diphosphate (GDP) binding and BAT mitochondrial uncoupling protein (UPC) mRNA levels in 4- and 24-month-old F-344 rats following forskolin administration. We also examined the forskolin-induced change in body temperature in 4-month-old rats. In some instances, the results were compared with administration of the specific ₃-adrenergic agonist, CGP-12177. Forskolin (3.5 mg/kg) increased oxygen consumption but decreased body temperature. In subsequent experiments the BAT was unilaterally denervated. In these rats, the forskolin-(1.8 mg/kg) stimulated increase in oxygen consumption was similar in young and old rats. Forskolin increased GDP binding and UCP mRNA levels in both the denervated and innervated BAT pads. The increases were equal or greater in the BAT from senescent rats. These findings, coupled with our previous report of an impaired CGP-12177-stimulated increase in GDP binding in senescent rats, suggests ₃-adrenergic-stimulated, but not post-receptor-stimulated, thermogenesis is diminished with age.     

The increase in the intracellular Ca2+ concentration induced by mechanical stimulation is propagated via release of pyrophosphorylated nucleotides in mammary epithelial cells

Mechanical stimulation of one mammary tumor cell in culture induced an increase in its intracellular calcium concentration which spread to surrounding cells. The increase in calcium can also be induced by addition of a solution in which cultured mammary tumor cells were stimulated by repeated pipetting (solution after pipetting cells, SAPC). The activity of the SAPC was completely abolished by treatment with snake venom phosphodiesterase or pyrophosphatase. Uridine triphosphate (UTP), uridine diphosphate (UDP) and ATP (1 M each) were detected in the SAPC, whereas 5-UMP and 5-AMP were produced by phosphodiesterase digestion. A mixture of UTP, UDP and ATP (1 M each) elicited a calcium response which was comparable to that induced by SAPC, while UTP, UDP or ATP alone at 1 M elicited a small increase in calcium concentration in mammary tumor cells. Suramin, a competitive antagonist of P₂ purinoceptors, diminished the spreading of the calcium wave induced by mechanical stimulation. It also blocked the responses to SAPC, UTP, UDP and ATP. These findings suggest that the mechanical stimulation results in the release of UTP, UDP and ATP into the extracellular space which mediates induction of the spreading calcium response via P_2U-type purinoceptors.     

Receptors and G proteins as primary components of transmembrane signal transduction

Seven-transmembrane receptors signal through nucleotide-binding proteins (G proteins) into the cell. G proteins are membrane-associated proteins composed of three subunits termed , and , of which the G subunit classifies the heterotrimer. So far, 23 different mammalian G subunits are known, which are grouped in four subfamilies (G_s, G_i, G_q, G₁₂) on the basis of their amino acid similarity. They carry an endogenous GTPase activity allowing reversible functional coupling between ligand-bound receptors and effectors such as enzymes and ion channels. In addition, five G and seven G subunits have been identified which form tightly associated heterodimers. Upon activation by a ligand-bound receptor the G protein dissociates into G and G, which both transmit signal by interacting with effectors. On the G protein level, specificity and selectivity of the incoming signal is accomplished by G protein trimers composed of distinct subunits. On the other hand, many receptors have been shown to activate different G proteins, thereby regulating diverse signal transduction pathways.Abbreviations CT Cholera toxin - PT Pertussis toxin     

Effect of endurance exercise on fibre type composition and muscle weight of reinnervating rat plantaris muscle

The purpose of this study was to evaluate the effect of endurance exercise on the histochemistry and wet weight of the reinnervating rat plantaris muscle. Two groups of young female Wistar rats (6 weeks old), 1 sedentary denervated control (n=13) and 1 excercised denervated experimental (n=17), were denervated unilaterally by cutting and resecting the sciatic nerve. To effect reinnervation a skin grafting operation was carried out on the nerve so that the gap caused by resection was bridged. The third group was the sedentary non-denervated normal control (n=10). A progressive training program of 18 weeks of treadmill running was carried out by the experimental group. Approximately 5 months after denervation, the plantaris muscles were studied histochemically for reduced nicotinamide adenine dinucleotide diaphorase (NADH-D) and mitochondrial alpha-glycerophosphate dehydrogenase (alpha-GPD) activities. Fibres were classified as red, white, or intermediate with NADH-D. Alpha-GPD differentiates intermediate from red fibre types in case of difficulty in differentiating these fibre types from each other with NADH-D. The weight of the reinnervated plantaris muscle increased significantly after exercise. The exerise did not change the fibre type proportions — including red fibre type — in the deep region of the reinnervating plantaris. There were significant differences between normal control and denervated control or experimental groups in histochemical fibre populations in the deep region of the plantaris. The findings of this study suggest that: (a) treadmill running did not increase the oxidative capacity of the deep region of the reinnervating rat plantaris muscle; (b) treadmill training did not damage the reinnervating plantaris; (c) the presence of type grouping following reinnervation was not affected by training (exercise did not interfere with reinnervation).     

Effects of muscarinic blockade on the thermic effect of oral or intravenous carbohydrate

Summary Muscarinic blockade by atropine has been shown to decrease the thermic effect of a mixed meal, but not of intravenous glucose. To further delineate the mechanisms involved in the atropine-induced inhibition of thermogenesis after a meal, plasma substrate and hormone concentrations, energy expenditure (EE) and substrate oxidation rates were measured before and during a continuous glucose infusion (44.4 mol·kg^–1·min^–1) with or without atropine. After 2 h of glucose infusion, a 20-g oral fructose load was administered while the glucose infusion was continued. Plasma insulin concentrations attained a plateau at 596 (SEM 100) pmol·l^–1 after 120 min of glucose infusion and were not affected by muscarinic blockade; plasma glucose concentrations peaked at 13.3 (SEM 0.5) mmol·l^–1 at 90 min and decreased progressively thereafter; no difference was observed with or without atropine. Plasma free fatty acid and glucagon concentrations, with or without atropine, were both decreased to 201 (SEM 18) mol·l^–1 and 74 (SEM 4) ng·l^–1, respectively, after 2 h of glucose infusion, and were not further suppressed after oral fructose. Carbohydrate oxidation rates (CHO_ox) increased to 20.8 (SEM 1.4) mol·kg^–1·min^–1 and lipid oxidation rates (L_ox) decreased to 1.5 (SEM 0.3) mol·kg^–1·min^–1 between 90 and 120 min after the beginning of glucose infusion and were not affected by atropine. Glucose-induced thermogenesis was similar with [6.5% (SEM 1.4%) of basal EE] or without [6.0% (SEM 1.0%), NS) muscarinic blockade during the 30 min preceding fructose ingestion. During the second half-hour after fructose ingestion, atropine infusion inhibited markedly the stimulation of CHO_ox [+2.8 (SEM 1.0) mol·kg^–1·min^–1 vs +6.9 (SEM 1.0) mol·kg^–1·min^–1, saline, P<0.02] and the suppression of L_ox [–0.8 (SEM 0.2) mol·kg^–1·min^–1 vs –1.4 (SEM 0.2) mol·kg^–1·min^–1, saline, P<0.05]. Carbohydrate-induced thermogenesis during the second half-hour after fructose ingestion, increased to 13.0% (SEM 2.0%) without atropine and was suppressed to 7.7% (SEM 1.9%) (P< 0.05, vs saline) with atropine. It was concluded that muscarinic blockade suppressed the increase of thermogenesis observed after oral fructose, but not during intravenous glucose infusion and that this suppression occurred independently of alterations of plasma insulin concentrations.