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R F Gilmour

Publications and source records attributed to R F Gilmour.

At least 37 records · Page 2Linked to original sources
PubMed1996

Phenylephrine-induced ventricular arrhythmias in dogs with inherited sudden death.

INTRODUCTION: Dogs with an inherited predisposition to sudden death display ventricular arrhythmias having certain characteristics, such as pause dependence, that are suggestive of early afterdepolarization-induced triggered activity. We hypothesized that alpha-adrenergic stimulation may facilitate the development of these arrhythmias by inducing a reflex bradycardia and by exerting a direct myocardial effect. METHODS AND RESULTS: Twenty affected dogs and 7 unaffected dogs were studied. The incidence and severity of ventricular arrhythmias were determined after administration of phenylephrine (0.01 mg/kg IV), with or without pretreatment with propranolol (0.1 to 0.3 mg/kg IV), atropine (0.04 mg/kg IV), or prazosin (0.5 mg/kg IV). Third-degree heart block was induced by AV nodal ablation in 4 affected dogs. Phenylephrine increased ventricular arrhythmias in affected dogs, with or without pretreatment with propranolol, but did not induce ventricular arrhythmias in unaffected dogs. In dogs with intact AV nodal conduction, atropine increased sinus rate, which suppressed baseline and phenylephrine-induced arrhythmias. In dogs with heart block, arrhythmias were increased during baseline and after phenylephrine, with or without pretreatment with atropine. Prazosin and overdrive ventricular pacing suppressed phenylephrine-induced arrhythmias. CONCLUSION: Phenylephrine increases ventricular arrhythmias in dogs with inherited sudden death via both an induction of reflex bradycardia and a direct myocardial effect. Superimposition of heightened alpha-adrenergic and vagal tone may facilitate the development of sudden death in these animals.

Animals↗
PubMed1996

A factor from Trypanosoma cruzi induces repetitive cytosolic free Ca2+ transients in isolated primary canine cardiac myocytes.

An unusual 120-kDa alkaline peptidase contained in a trypomastigote soluble fraction (TSF) of Trypanosoma cruzi is associated with the induction of repetitive Ca2+ transients and subsequent invasion by the parasite of a number of mammalian cell lines, including tissue culture L6E2 myoblasts (B. A. Burleigh and N. W. Andrews, J. Biol. Chem. 270:5172-5180, 1995; S. N. J. Moreno, J. Silva, A. E. Vercesi, and R. Docampo, J. Exp. Med. 180:1535-1540, 1994; A. Rodríguez, M. G. Rioult, A. Ora, and N. W. Andrews, J. Cell Biol. 129:1263-1273, 1995; I. Tardieux, M. H. Nathanson, and N. W. Andrews, J. Exp. Med. 179:1017-1022, 1994). Using single cell spectrofluorometry and whole-cell patch clamping, we show that TSF produces rapid repetitive cytosolic Ca2+ transients (each associated with cell contraction) in primary cardiac myocytes isolated from dogs. The response of myocytes to TSF was dose dependent in that increasing numbers of cells responded to increasing concentrations of TSF. The TSF-induced Ca2+ transients could be obliterated when TSF was heated or treated with trypsin or the protease inhibitor leupeptin. Aprotinin, pepstatin A, and E-64 did not affect TSF activity. The TSF-induced Ca2+ transients and trypomastigote cell invasion could not be inhibited by alpha (prazosin)- or beta (propanolol)-adrenergic blockers or L-type Ca2+ channel blockers (verapamil, nisoldipine, or cadmium) or by removal of extracellular Ca2+. However, inhibition of pertussis toxin-sensitive G proteins and Ca2+ release from the sarcoplasmic reticulum (with thapsigargin or ryanodine) prevented the TSF-induced Ca2+ transients and cell invasion by trypomastigotes. These data suggested that cardiac myocyte pertussis toxin-sensitive G proteins are associated with the regulation of TSF-induced Ca2+ transients and myocyte invasion by trypomastigotes but are independent of Ca2+ entry into the cytosol via L-type Ca2+ channels. The Ca2+ transients are dependent on release of Ca2+ from sarcoplasmic reticulum Ca2+ stores, but this release is not dependent on extracellular Ca2+ or on the classic model of Ca2+ -induced Ca2+ release in cardiac myocytes. Further, subthreshold depolarizations, together with cell contraction as demonstrated by whole-cell patch clamping, occurred with each Ca2+ transient. However, the depolarizations were of magnitude insufficient to generate an action potential, providing further evidence for a lack of dependence on L-type Ca2+ channels and other voltage-dependent channels (Na+ and K+ channels) in the generation of TSF-induced Ca2+ transients. Our findings suggest that primary canine cardiac myocytes respond to TSF and parasite invasion in ways similar to those of the in vitro cell lines studied to date. Since cardiac myocytes are primary targets for T. cruzi in the vertebrate host, our study indicates that TSF may play a role in the pathogenesis of Chagas' disease in humans.

Animals↗
PubMed1996

Relationship of ventricular tachycardia to sleep/wakefulness in a model of sudden cardiac death.

Death from some childhood disorders such as sudden infant death syndrome and the congenital long QT syndrome are associated with specific behaviors such as sleep or emotional stress. We studied young German shepherd dogs that die suddenly during presumed sleep. These dogs have inherited ventricular tachycardia (VT) which is most frequent during sinus bradycardia and sinus arrhythmia. We hypothesized that the number of VT complexes (three or more consecutive ectopic complexes) would be greatest during sleep. Moreover, we hypothesized that pauses in the sinus rhythm of greater than 1000 ms would be greatest in the behavior with the most frequent VT. Behavioral states [excited, ambulatory, sitting, lying, rapid eye movement (REM) sleep] were quantified from 24-h video recordings of seven dogs. VT and pauses were quantified for each behavior using simultaneously recorded ECGs. A multivariate model was used to analyze the results. After controlling for time of day, lying, and REM sleep were significantly (p < 0.02) associated with VT, whereas more active behaviors were not. Time of day also independently affected the number of VT complexes. However, behavior and time of day did not account for all of the variability in the number of VT complexes. Pauses were significantly associated with behavior, with the highest number of pauses occurring during lying and REM sleep. However, pauses were not always associated with VT, indicating that a pause was a necessary, but not sufficient, condition for the development of VT. These results suggest that modulation of VT incidence in these animals is multifactorial and that the highest number of VT complexes is associated with the bradycardia that accompanies REM sleep.

Animals↗
PubMed1995

Reduction of the transient outward potassium current in a canine model of Chagas' disease.

The effects of Chagas' disease, an important cause of cardiac arrhythmias and cardiomyopathy, on cellular electrical properties were determined in epicardial tissue from normal dogs and dogs infected with Trypanosoma cruzi for 20-25 days (25 DPI), at the time of maximum parasitemia, and for 125-140 days (140 DPI) after the parasitemia had subsided. At 25 DPI, phase 1 repolarization of the action potential was attenuated and the transient outward current (Ito) was reduced from 10.2 +/- 0.5 to 5.5 +/- 0.6 pA/pF. No differences were apparent between infected and normal cells in the time constants of current decay (25.6 +/- 4.0 and 22.8 +/- 1.3 ms, respectively) or in the steady-state inactivation parameters (V1/2 = -34.1 +/- 3.6 and -34.6 +/- 1.4 mV and k = 6.3 +/- 1.8 and 4.0 +/- 0.3, respectively). The rapid phase of recovery from inactivation was nearly eliminated in infected myocytes, whereas the slower phase was unaffected. Phase 1 repolarization and Ito density at 140 DPI were not significantly different from normal cells. Thus T. cruzi acutely inhibited Ito in epicardial myocytes, an effect that was reversed with abatement of the parasitemia.

Action Potentials↗
PubMed1995

Developmental changes of action potential configuration and I(to) in canine epicardium.

Developmental changes of the transient outward current (I(to)) and action potential configuration were determined in canine epicardium ranging in age from fetal to 60 wk. The contributions of I(to) to rapid initial repolarization and to terminal repolarization were estimated by measuring the amplitude of phase 1 of the action potential and action potential duration, respectively. Phase 1 amplitude decreased progressively from fetal to 40 wk and remained constant thereafter. Action potential duration decreased from fetal to 2 wk, increased to 20 wk, and tended to decrease thereafter. Peak I(to) at +40 mV increased progressively from 2 to 60 wk. However, I(to) density was less at 2-10 wk than at 20-60 wk. The time constant of decay of I(to) increased with age from 2 to 60 wk, whereas the steady-state voltage dependence of inactivation did not vary with age. The time constant for the initial rapid phase of recovery from inactivation decreased from 2 to 10 wk and remained constant thereafter. The time constant for the more slowly evolving phase did not vary with age. The observation that the age-dependent reduction in phase 1 amplitude did not necessarily coincide with significant increases in I(to) density suggests that maturation of other ionic currents or transport mechanisms may contribute to developmental alterations of phase 1 repolarization.

4-Aminopyridine↗
PubMed1995

Biphasic restitution of action potential duration and complex dynamics in ventricular myocardium.

The purpose of this study was to determine whether biphasic restitution of action potential duration (APD) in ventricular muscle permits the development of complex dynamic behavior. Such behavior is expected because of the steep ascending slope of restitution and the presence of a maximum. Action potentials recorded from strips of epicardial muscle in which biphasic APD restitution occurred demonstrated a characteristic pattern of phase locking during progressive shortening of the pacing cycle length. 1:1 locking was replaced by irregular dynamics, which in turn was replaced by higher order periodic behavior (eg, 8:8 locking), then by 2:2 locking, and finally by 2:1 locking. Similar patterns of dynamic behavior were produced in a computer model by using a piecewise linear approximation of biphasic APD restitution. Features of APD restitution that were critical determinants of irregular dynamics included the slopes of the ascending and the nonmonotonic regions. These results suggest that rate-related alterations of APD and refractoriness may be affected significantly by small nonmonotonicities in APD restitution.

Action Potentials↗
PubMed1994

Dynamics of circus movement re-entry across canine Purkinje fibre-muscle junctions.

1. To determine the cellular electrophysiological mechanisms for unidirectional conduction block and re-entrant excitation, single cycles of circus movement re-entry were induced in canine Purkinje fibre-papillary muscle preparations containing two Purkinje fibre-muscle junctions (PMJs). The preparations were mounted in a partitioned tissue bath that permitted independent superfusion of each PMJ. The pre-existing dispersion of refractoriness between PMJs was accentuated by superfusing PMJ1 with normal Tyrode solution or Tyrode solution containing 6-8 mM KCl and superfusing PMJ2 with Tyrode solution containing 0.5 mM heptanol and 4-10 mM KCl. 2. Premature stimuli delivered to the Purkinje fibre induced unidirectional anterograde conduction block at PMJ2. Conduction proceeded from Purkinje cells to papillary muscle at PMJ1 and from papillary muscle retrogradely across the previously blocked PMJ2. 3. The difference in refractory periods between the two PMJs defined a range of premature coupling intervals within which re-entry was inducible. Conduction block at the PMJ occurred in papillary muscle at short coupling intervals and in the Purkinje fibre at longer intervals. 4. Once initiated, re-entry could be reset or annihilated by properly timed subthreshold current pulses delivered to cells at the PMJ. 5. To define better the mechanisms for conduction block and re-entry, an analytical model was developed using non-linear regression analysis to derive equations from the experimental results. Varying parameters within the constraints of the model reproduced the key features of the rate-dependent conduction block observed experimentally. Critical elements of the model included the induction of significant activation delays at short diastolic intervals and a reduction in the rate of action potential duration restitution after exposure to heptanol. 6. These results help to establish the conditions necessary for induction of one-dimensional circus movement re-entry and to define the roles of non-linearities of activation delay and excitability in the dynamics of conduction block at the PMJ.

Animals↗
PubMed1994

Modulation of the excitability of avian peripheral nerves by vitamin D: relation to calbindin-D28k, calcium status and lipid composition.

Calbindin-D28k (CaBP), previously localized in some of the cell bodies of ganglia of the avian intestinal (Remark's) nerve, was shown to be vitamin D-dependent. In the present studies, the effect of vitamin D3 on electrophysiological properties of this nerve was examined in vitro. Electrical stimulation of the nerve yielded a compound action potential with two primary components, Peaks I and II. Peak II, suppressed by hexamethonium bromide or Ca(2+)-free buffer, is synaptically mediated. The transit time between the two peaks was unaffected by vitamin D3. The apparent conduction velocity, defined as [(activation time + transit time)/nerve length], was increased by vitamin D-deficiency and decreased by vitamin D3 repletion, the latter decrease due entirely to an increase in activation time. Activation time after vitamin D-repletion was correlated with an increase in CaBP and plasma Ca2+ levels. However, normalization of plasma Ca2+ by supplementation of vitamin D-deficient diets with excess calcium (2.5 and 4.0%) also resulted in an increase in activation time, without affecting neuronal CaBP levels. Vitamin D3 also decreased the conduction velocity and increased CaBP of the vagus nerve and, by lipid analysis, was shown to increase and decrease its phosphatidylcholine and phosphatidylethanolamine content, respectively, and to decrease its phospholipid/cholesterol ratio. Modulation of peripheral nerve activity by vitamin D3 is related to calcium status and perhaps to changes in lipid composition. The functional role of CaBP in the behaviour of this complex nerve remains unknown.

Animals↗
PubMed1994

The sensitivity of pressure specific bladder volume versus total bladder capacity as a measure of bladder storage dysfunction.

Assessment of bladder storage function requires an accurate measure of bladder capacity and pressure. Pressure specific bladder volume is the volume that a bladder can accommodate at a specific pressure. A total of 21 consecutive children with neurogenic bladders who were candidates for bladder augmentation based on standard clinical criteria (upper urinary tract deterioration, incontinence and infection) was studied to determine the efficacy of pressure specific bladder volume as a measure of bladder dysfunction. Urodynamic indexes were compared to previously established nomograms. All 21 patients had bladder volumes at pressures of 30 cm. water or less, which decreased below the 5th percentile as determined by the nomogram. In 7 patients (33%) normal total bladder capacity was achieved at the expense of elevated storage pressures. Pressure specific bladder volume provides a better measure of bladder storage function than total bladder capacity because it relates volume to intravesical pressure, does not rely on a subjective end point to bladder filling, and is objective and reproducible.

Adolescent↗
PubMed1994

Loss of elasticity in dysfunctional bladders: urodynamic and histochemical correlation.

To store adequate volumes of urine at low safe pressures an elastic bladder wall is required. We developed 2 new techniques to measure this ability in our urodynamic laboratory: pressure specific bladder volume, which measures the bladder capacity at a given pressure, and dynamic analysis of bladder compliance. Recently, morphometric and histochemical techniques have been used to determine the relative volume of connective tissue in the bladder wall and to measure the 2 major types (I and III) of collagen within the bladder wall. These methods quantitate 3 parameters of bladder ultrastructure: 1) relative volume of per cent connective tissue, 2) ratio of connective tissue to smooth muscle and 3) ratio of type III to type I collagen. These parameters have been shown to be abnormally elevated in patients with dysfunctional bladders compared to normals. The purpose of the study was to describe the ultrastructural changes that occur in the wall of dysfunctional bladders and to determine the ability of these new urodynamic techniques to detect reliably the clinical effect of these histological changes. The study included 29 consecutive patients with dysfunctional bladders necessitating bladder augmentation. All patients had upper tract changes and/or were incontinent despite treatment with clean intermittent catheterization and pharmacotherapy. Preoperative urodynamic evaluation included measurement of the total bladder capacity, pressure specific bladder volume and dynamic analysis of bladder compliance. Full thickness bladder biopsies were obtained from the dome of the bladders during augmentation. The per cent connective tissue and the ratio of connective tissue to smooth muscle were determined for all patients, and 4 unselected patients from this group had the ratio of type III to type I collagen determined. These histological results were compared to previously established normal values. All 29 patients had a decreased pressure specific bladder volume and dynamic analysis of bladder compliance, whereas 9 had a normal total bladder capacity. The per cent connective tissue was 35.19 +/- 2.84 and ratio of connective tissue to smooth muscle was 0.60 +/- 0.08 compared to normal values of 10.6 +/- 0.020 and 0.131 +/- 0.021, respectively (p < 0.05). Ratio of type III to type I collagen was also significantly elevated in the 4 samples analyzed (30.53 +/- 1.37 versus 24.00 +/- 2.50, p < 0.05). We conclude that poor storage function of poorly compliant bladders is secondary to an alteration in the connective tissue content of the bladder wall. Furthermore, these pathological ultrastructural changes are universally reflected by an abnormally low pressure specific bladder volume and dynamic analysis of bladder compliance. This strong association validates the use of these parameters and suggests that they are urodynamic indicators of a loss of elasticity in bladder wall.

Adolescent↗
PubMed1994

Bladder augmentation: ureterocystoplasty versus ileocystoplasty.

The primary advantages of augmentation ureterocystoplasty include the absence of mucus, lack of electrolyte absorption from the augmenting segment and the avoidance of gastrointestinal complications. We tested whether the ureteral patch offers sufficient biomaterial to increase adequately the storage efficiency of dysfunctional bladders. Between April 1989 and November 1992, 8 children with unilaterally dilated and tortuous ureters underwent bladder augmentation using detubularized reconfigured megaureter. Clinical and urodynamic outcomes were compared between these patients and a control group of 8 children matched in age and diagnosis who had undergone ileocystoplasty during the same time. Total bladder capacity, pressure specific bladder volume at pressure less than 30 cm. water, dynamic analysis of bladder compliance, continence and upper tract status were compared between the 2 groups before and after augmentation. Preoperatively, all 16 patients were incontinent with high pressure, small capacity bladders, and all had upper tract changes. Postoperatively, the mean total bladder capacity was 417 ml. in the ureterocystoplasty group and 381 ml. in the ileocystoplasty group (p > 0.05), while the mean pressure specific bladder volume was 413 and 380 ml. (p > 0.05), respectively. Pressure specific bladder volume and dynamic bladder compliance were normal in 7 of 8 patients (87.5%) in the ureterocystoplasty group. All patients in the ileocystoplasty group had normal postoperative urodynamics. We conclude that megaureters subtending effete kidneys may be used to improve the storage function of dysfunctional bladders to the same extent as that achieved with ileum without the complications pursuant to ileocystoplasty, and that the improvement is maintained long term.

Adolescent↗
PubMed1994

Reduction of the transient outward potassium current in canine X-linked muscular dystrophy.

BACKGROUND: The xmd dog develops a cardiomyopathy similar to that seen in Duchenne muscular dystrophy patients. In both the canine and human diseases, ECG abnormalities may precede the development of overt cardiac pathological lesions. The purpose of this study was to determine whether specific cellular electrical abnormalities occur in dystrophic ventricular tissue. METHODS AND RESULTS: Action potentials were recorded in epicardial tissue strips obtained from normal and xmd dogs. Phase 1 amplitude was increased from 86.8 +/- 2.7 mV in normal dogs to 94.3 +/- 1.8 mV in xmd dogs (mean +/- SEM; P < .05). The 4-aminopyridine-sensitive transient outward potassium current (Ito), as recorded in isolated epicardial myocytes using the whole-cell patch-clamp technique, was reduced in xmd dogs compared with age-matched normal dogs. Cell capacitance also was reduced significantly in xmd compared with normal cells, as was the current density (3.6 +/- 0.3 versus 5.4 +/- 0.8 pA/pF, respectively). No differences were observed in the time constants of current decay or in the kinetics of recovery from inactivation between groups. The slope factor (k) of steady-state inactivation was significantly greater in xmd compared with normal cells (7.2 +/- 0.9 versus 5.4 +/- 0.5, respectively), whereas the V1/2 of inactivation did not differ (-38.2 +/- 2.4 versus -36.8 +/- 1.6 mV, respectively). CONCLUSIONS: These data indicate that the magnitude of Ito is reduced in dystrophic epicardial myocytes, resulting in an increase in phase 1 amplitude. The reduction of Ito may alter the balance of inward and outward currents in dystrophic myocardium and thereby contribute to the development of cardiac pathology.

Action Potentials↗
PubMed1993

A new technique for dynamic analysis of bladder compliance.

We propose an alternative method of measuring compliance that takes into account the multiple phases of bladder filling. We describe our new technique, dynamic compliance analysis, and evaluate its clinical applicability. To perform the analysis we digitized a cystometrogram curve at a sampling rate of 2 samples per second using an MS-DOS computer system. A program designed to retrieve the stored data was used to analyze the subtracted bladder pressure. The result yielded a value of compliance every half second that was then plotted on an x-y graph, with instantaneous compliance as the dependent variable and per cent of total volume infused as the independent variable. To determine the clinical applicability of this technique we chose 63 curves from clinically normal patients. The results of the dynamic compliance analyses were predictable. The dynamic compliance values for the normal group had a minimum that was always greater than 10 ml./cm. water throughout the tonus limb (phase 2) of the cystometrogram. We conclude that dynamic compliance analysis yields more information about bladder response during filling, similar to the stress-strain curve used in the study of solid mechanics.

Biomechanical Phenomena↗
PubMed1993

What volume can a child normally store in the bladder at a safe pressure?

To determine what volume a child can normally store in the bladder at a safe pressure 923 pediatric urodynamic studies were reviewed, and 69 examinations done on 17 boys and 52 girls were considered normal. Patient ages were recorded and body surface areas were calculated. A continuous intermediate flow water cystometrogram had been performed. Total bladder capacity in milliliters, full resting pressures (cm. water), and the volumes (milliliters) and percentages of the total bladder capacity stored at detrusor pressures of less than 10, 20, 30 and 35 cm. water were measured. We found that 98.1% of the total bladder capacity could be stored at a detrusor pressure of less than 20 cm. water in more than 95% of the children independently of age or body surface area and 99.9% could be stored at a detrusor pressure of less than 30 cm. water. An approximation of the minimal acceptable total bladder capacity for age can be calculated by 16(age) + 70 in ml. According to our results, we proposed criteria for good storage characteristics of the bladder in children.

Body Surface Area↗
PubMed1992

The efficiency of bladder emptying in the prune belly syndrome.

From 1956 to 1991, 49 cases of the prune belly syndrome were seen at our institution. Voiding information and/or 1 or more urodynamic studies were available in 30 male and 4 female patients. Analysis of multiple urodynamic studies during long-term followup periods ranging from 6 months to 19 years, with particular regard to any reconstructive procedures performed, revealed that voiding in the prune belly syndrome is variable, with 44% of the patients achieving spontaneous voiding and 56% requiring clean intermittent catheterization. The ability to void or need for clean intermittent catheterization was by no means permanent, indicating the need for meticulous followup. The 3 distinct voiding patterns observed included an approximately normal pattern, prolonged voiding with a low peak and an intermittent pattern. These 3 voiding patterns did not correlate with residual volumes. Comparison of urodynamic voiding parameters between reconstructed voiding patients and nonreconstructed voiding patients did not show significant differences.

Adolescent↗
PubMed1991

Duchenne's cardiomyopathy in a canine model: electrocardiographic and echocardiographic studies.

Thirteen dogs affected with X-linked Duchenne's muscular dystrophy and 11 female carrier dogs were studied by electrocardiography (ECG) and echocardiography. Twelve of the affected dogs were studied as immature animals and followed at 1 to 6 month intervals until they were 7 to 46 months of age. Compared with control dogs, affected dogs had significantly increased (p less than 0.02) Q/R ratios in ECG leads II, III, aVF, CV6LL (V2) and CV6LU (V4). Carrier dogs had significantly increased (p less than 0.02) Q/R ratios in leads V2 and V4. The Q/R ratio increased in three of six dogs followed up from age 6 months to greater than 2 years. The PR intervals were significantly shorter (p less than 0.02) in affected dogs. Ventricular arrhythmias were identified in four of six mature affected dogs. Two-dimensional echocardiography revealed distinctive hyperechoic lesions in 12 of the 13 affected dogs and in 6 of the 11 carrier dogs. Hyperechoic lesions corresponded to calcified myocardium and surrounding dense connective tissue. This study establishes the dog affected with Duchenne's muscular dystrophy as an animal model of Duchenne's cardiomyopathy and demonstrates that the heart in carrier dogs is affected by the dystrophic process.

Animals↗
PubMed1991

Dietary taurine deficiency and dilated cardiomyopathy in the fox.

Taurine deficiency has been implicated as a potential cause of dilated cardiomyopathy. However, the relationship between taurine and myocardial function is presently unclear. The purpose of this study was to determine whether dilated cardiomyopathy in the fox is associated with dietary taurine deficiency. A total of 68 foxes from farms with a history of death caused by dilated cardiomyopathy and 14 foxes from a farm with no history of dilated cardiomyopathy were studied. Dilated cardiomyopathy was diagnosed by echocardiography in 48% of the foxes from one farm with a positive history and in none of the foxes from the control farm. Foxes less than 9 months of age were more commonly affected than older foxes (p = 0.03). Plasma taurine concentrations were significantly less (p less than 0.01) in foxes that had dilated cardiomyopathy (26.8 +/- 16.4 nmol/ml) than in the control foxes (99.3 +/- 60.2 nmol/ml). A significantly higher (p less than 0.01) incidence of dilated cardiomyopathy was present in foxes with a history of a sibling or offspring that died of dilated cardiomyopathy than in foxes without a family history of cardiac death. In one fox with dilated cardiomyopathy that was tested, the myocardial taurine concentration was lower (1.7 mumol/gm wet weight) than that of control foxes (7.3 +/- 1.6 mumol/gm wet weight). Hepatic cysteinesulfinic acid decarboxylase activity was significantly less (p less than 0.001) in foxes with dilated cardiomyopathy (0.97 +/- 0.2 nmol/mm.mg protein) than in control foxes (2.11 +/- 0.07 nmol CO2/mm.mg protein).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗