Appearance of cholinergic myenteric neurons during enteric nervous system development: comparison of different ChAT fluorescent mouse reporter lines.

BACKGROUND: Cholinergic neurons have been identified with the acetylcholine synthetic enzyme choline acetyltransferase (ChAT). However, ChAT is difficult to localize in newly differentiated peripheral neurons making the study of cholinergic neuronal development problematic. Consequently, researchers have used mouse reporter lines to indicate the presence of ChAT. METHODS: Our objective was to determine which ChAT reporter line was the most sensitive indicator of ChAT expression. We utilized two different fluorescent ChAT reporter lines (ChAT-GFP and ChAT-Cre;R26R:floxSTOP:tdTomato) together with immunolocalization of ChAT protein (ChAT-IR) to characterize the spatial and temporal expression of ChAT in myenteric neurons throughout enteric nervous system (ENS) development. KEY RESULTS: ChAT-IR cells were first seen in the intestine at E10.5, even within the migration wavefront of neural precursors. Myenteric neurons within the distal small intestine (dSI) and proximal colon were first labeled by ChAT-IR, then ChAT-GFP, and finally ChAT-Cre tdTomato. The percentage of ChAT-IR neurons is equivalent to adult levels in the dSI by E13.5 and proximal colon by P0. After these stages, the percentages remained relatively constant throughout development despite dramatic changes in neuronal density. CONCLUSIONS & INFERENCES: These observations indicate that neurotransmitter expression occurs early and there is only a brief gap between neurogenesis and neurotransmitter expression. Our finding that the proportion of ChAT myenteric neurons reached adult levels during embryonic development suggests that the fate of cholinergic neurons is tightly regulated and that their differentiation might influence further neuronal development. ChAT-GFP is a more accurate indicator of early ENS cholinergic neuronal differentiation than the ChAT-Cre;R26R:floxSTOP:tdTomato reporter mouse.

Lack of sigma-1 receptor exacerbates ALS progression in mice.

The function of the sigma-1 receptor (S1R) has been implicated in modulating the activity of various ion channels. In the CNS S1R is enriched in cholinergic postsynaptic densities in spinal cord motoneurons (MNs). Mutations in S1R have been found in familial cases of amyotrophic lateral sclerosis (ALS). In this study we show that a knockout of S1R in the SOD1*G93A mouse model of ALS significantly reduces longevity (end stage). Electrophysiological experiments demonstrate that MN of mice lacking S1R exhibit increased excitability. Taken together the data suggest the S1R acts as a brake on excitability, an effect that might enhance longevity in an ALS mouse model.

Altered neuronal density and neurotransmitter expression in the ganglionated region of Ednrb null mice: implications for Hirschsprung's disease.

BACKGROUND: Hirschsprung's disease (HSCR) is a congenital condition in which enteric ganglia, formed from neural crest cells (NCC), are absent from the terminal bowel. Dysmotility and constipation are common features of HSCR that persist following surgical intervention. This persistence suggests that the portion of the colon that remains postoperatively is not able to support normal bowel function. To elucidate the defects that underlie this condition, we utilized a murine model of HSCR. METHODS: Mice with NCC-specific deletion of Ednrb were used to measure the neuronal density and neurotransmitter expression in ganglia. KEY RESULTS: At the site located proximal to the aganglionic region of P21 Ednrb null mice, the neuronal density is significantly decreased and the expression of neurotransmitters is altered compared with het animals. The ganglia in this colonic region are smaller and more isolated while the size of neuronal cell bodies is increased. The percentage of neurons expressing neuronal nNOS and VIP is significantly increased in Ednrb nulls. Conversely, the percentage of choline acetyltransferase (ChAT) expressing neurons is decreased, while Substance P is unchanged between the two genotypes. These changes are limited to the colon and are not detected in the ileum. CONCLUSIONS & INFERENCES: We demonstrate changes in neuronal density and alterations in the balance of expression of neurotransmitters in the colon proximal to the aganglionic region in Ednrb null mice. The reduced neuronal density and complementary changes in nNOS and ChAT expression may account for the dysmotility seen in HSCR.

Expectancy-related modulations of neural oscillations in continuous performance tasks.

Analysis of neural oscillations in the electroencephalogram (EEG) during cognitive tasks provides valuable information about underlying neuronal processing not accessible by other methods such as event-related potentials (ERPs) and the BOLD signal in fMRI. We investigated neural substrates of motor preparation and expectancy by analyzing neural oscillations of healthy subjects performing the AX continuous performance task (AX-CPT), a task widely used to evaluate processes such as cognitive control, motor preparation and anticipatory and sustained attention. The task consists of letters presented sequentially on a monitor, and subjects are required to respond only when they see the letter A (cue) followed by the letter X (target). In this study, to emphasize expectation and motor preparation, three versions of AX-CPT were used in which the overall propensity to respond was differentially modulated, by changing the probability of the letter sequences. Neural activity was investigated in three time windows following presentation of the cue: sensory, evaluation and preparation. Alpha power was reduced following cue onset similarly in all versions of the task in both the sensory and evaluation periods, but in the later preparation period there were task dependent modulations. Alpha was decreased when an infrequent cue increased the chance of a response, and increased when a propensity to respond had to be overcome, possibly reflecting an anticipatory attentional mechanism to gate visuo-motor processing. Beta power was modulated by task and cue in both evaluation and preparation periods. In the latter, beta power reflected the propensity to respond and correlated both with amplitude of the contingent negative variation (CNV), an ERP that reflects response preparation, and with reaction time. Some clinical populations such as patients with schizophrenia or attention-deficit disorder show specific deficits when performing the AX-CPT. These results provide a basis for investigating the differential neural underpinnings of oscillatory cognitive control deficits observed in various patient populations.

Development of the sigma-1 receptor in C-terminals of motoneurons and colocalization with the N,N'-dimethyltryptamine forming enzyme, indole-N-methyl transferase.

The function of the sigma-1 receptor (S1R) has been linked to modulating the activities of ion channels and G-protein-coupled receptors (GPCR). In the CNS, the S1R is expressed ubiquitously but is enriched in mouse motoneurons (MN), where it is localized to subsurface cisternae of cholinergic postsynaptic densities, also known as C-terminals. We found that S1R is enriched in mouse spinal MN at late stages of embryonic development when it is first visualized in the endoplasmic reticulum. S1Rs appear to concentrate at C-terminals of mouse MN only on the second week of postnatal development. We found that indole-N-methyl transferase (INMT), an enzyme that converts tryptamine into the sigma-1 ligand dimethyltryptamine (DMT), is also localized to postsynaptic sites of C-terminals in close proximity to the S1R. This close association of INMT and S1Rs suggest that DMT is synthesized locally to effectively activate S1R in MN.

The sigma-1 receptor is enriched in postsynaptic sites of C-terminals in mouse motoneurons. An anatomical and behavioral study.

The sigma-1 receptor regulates various ion channel activity and possesses protein chaperone function. Using an antibody against the full sequence of the sigma-1 receptor we detected immunostaining in wild type but not in knockout mice. The receptor was found primarily in motoneurons localized to the brainstem and spinal cord. At the subcellular level the receptor is restricted to large cholinergic postsynaptic densities on the soma of motoneurons and is colocalized with the Kv2.1 potassium channel and the muscarinic type 2 cholinergic receptor. Ultrastructural analysis of the neurons indicates that the immunostained receptor is located close but separate from the plasma membrane, possibly in subsurface cisternae formed from the endoplasmic reticulum (ER), which are a prominent feature of cholinergic postsynaptic densities. Behavioral testing on a rotorod revealed that Sigma-1 receptor knockout mice remained on the rotorod for significantly less time (a shorter latency period) compared to the wild type mice. Together these data indicate that the sigma-1 receptor may play a role in the regulation of motor behavior.

Carvedilol reverses elevated pulmonary vascular resistance in a child with dilated cardiomyopathy.

There is little experience using beta-blocker therapy for the management of congestive heart failure (CHF) in children. We present the case of a child with idiopathic dilated cardiomyopathy and CHF, referred for cardiac transplantation, in whom carvedilol reversed elevated pulmonary vascular resistance.

Immediate feedback during academic testing.

Performance on two multiple-choice testing procedures was examined during unit tests and a final examination. The Immediate Feedback Assessment Technique provided immediate response feedback in an answer-until-correct style of responding. The testing format which served as a point of comparison was the Scantron form. One format was completed by students in introductory psychology courses during unit tests whereas all students used the Scantron form on the final examination. Students tested with Immediate Feedback forms on the unit tests correctly answered more of the final examination questions which were repeated from earlier unit tests than did students tested with Scantron forms. Also, students tested with Immediate Feedback forms correctly answered more final examination questions previously answered incorrectly on the unit tests than did students tested previously with Scantron forms.

Iodixanol pharmacokinetics in children.

The objective of this report was to study the elimination pharmacokinetics of iodixanol in children. Iodixanol (Visipaque, Nycomed Inc., Wayne, PA, USA) is a new iso-osmolar iodinated radiocontrast agent. We hypothesized that elimination of this agent would be dependent on age-related differences in renal clearance. Seven centers enrolled 43 patients. Cardiac catheterization was performed in 41 patients and cranial computed tomography in 2. Patients were entered into 5 age groups: newborn to <2 months, 2 to <6 months, 6 months to <1 year, 1 to <3 years, and 3 to 6 months of age that is comparable to normal adults. Prolonged elimination in children <6 months of age is related to renal immaturity.

Enteric neuroblasts require the phosphatidylinositol 3-kinase pathway for GDNF-stimulated proliferation.

The enteric nervous system (ENS) develops from neural crest cells that enter the gut, migrate, proliferate, and differentiate into neurons and glia. The growth factor glial-derived neurotrophic factor (GDNF) stimulates the proliferation and survival of enteric crest-derived cells. We investigated the intracellular signaling pathways activated by GDNF and their involvement in proliferation. We found that GDNF stimulates the phosphorylation of both the PI 3-kinase downstream substrate Akt and the MAP kinase substrate ERK in cultures of immunoaffinity-purified embryonic avian enteric crest-derived cells. The selective PI 3-kinase inhibitor LY-294002 blocked GDNF-stimulated Akt phosphorylation in purified crest cells, and reduced proliferation in cultures of dissociated quail gut. The ERK kinase (MEK) inhibitors PD 98059 and UO126 did not reduce GDNF-stimulated proliferation, although PD 98059 blocked GDNF-stimulated phosphorylation of ERK. We conclude that the PI 3-kinase pathway is necessary for the GDNF-stimulated proliferation of enteric neuroblasts.

P wave signal-averaged electrocardiogram as a new marker for atrial tachyarrhythmias in postoperative Fontan patients.

OBJECTIVES: This study was undertaken to determine the potential role of P wave signal-averaged electrocardiogram (PSAECG) for risk assessment of atrial tachyarrhythmias (ATs) in patients after Fontan operation. BACKGROUND: Onset of atrial flutter/fibrillation (AFF) in patients who have undergone Fontan operation for univentricular hearts constitutes an unfavorable clinical event associated with a high risk of cardiovascular complications. There is no data available on PSAECG in postoperative Fontan patients to predict potential susceptibility to ATs. METHODS: Twenty-four post-Fontan patients and 15 age-matched healthy subjects were prospectively studied with PSAECG, and the following measurements were made: filtered P wave duration (FPWD), P wave vector integrals (PINTs), root-mean-square voltage for the initial 30 ms (RMSi30), and duration of persistent amplitude signals <4 microV from the beginning of the P wave (Di4). RESULTS: The FPWDs were significantly longer in the study group patients with ATs when compared with the study group patients without ATs (p<0.01) and compared with the controls (p < 0.001). An FPWD cut point of 135 ms resulted in a sensitivity of 71% and a specificity of 81% in differentiating patients with ATs from patients without ATs among the postoperative Fontan patients. The PINT was significantly greater in Fontan patients with AFF and also without AFF when compared with controls (p<0.01, p<0.05, respectively). The RMSi30 and the Di4 were not significantly different between study and control groups. CONCLUSIONS: Signal-averaged P wave duration is significantly prolonged in postoperative Fontan patients. A prolonged signal-averaged P wave duration may be an effective noninvasive marker to predict risk of development of ATs in this patient group.

Expression of the GDNF receptors ret and GFRalpha1 in the developing avian enteric nervous system.

The formation of the enteric nervous system (ENS) from neural crest-derived cell precursors requires the growth factor glial cell line-derived neurotrophic factor (GDNF) and the receptors Ret and GDNF family receptor alpha 1 (GFRalpha1). We investigated the location(s), the timing, and the extent to which these GDNF receptors appear in the population of crest-derived precursors that form the avian ENS using immunohistochemistry and in situ hybridization. Sections and whole mounts of embryonic chick gastrointestinal tract were costained with antibodies to the receptors and to HNK-1, a marker for crest-derived cells. Neural crest-derived precursors migrate through the primitive esophagus to colonize the gizzard where an extensive cellular network forms. Ret-immunoreactivity (ir) was found in a network of cells in the gizzard at embryonic day (E)3.5. As development proceeded, Ret-immunoreactive cells appeared at progressively more caudal positions and were present in the colon at E7.5. Costaining with Ret and HNK-1 was performed to determine the number of Ret-immunoreactive cells in the crest-derived population. Ret appeared in some HNK-1 cells in the esophagus and gizzard at embryonic day (E)3.5. During development, the number of crest cells with Ret increased in the ganglia of the gizzard and small intestine. GFRalpha1-ir was also found in HNK-1 cells in the esophagus at E3.5 but did not appear in the gizzard until E4.5. Surprisingly, the colonizing vanguard of crest-derived cells lacked both Ret- and GFRalpha-ir. Between E4.5 and E6.5, the fraction of HNK-1-positive cells expressing GFRalpha1 increased considerably in the foregut. Ret and GFRalpha1 were coexpressed in many cells at E6.5, and the number of such cells increased as development progressed. In the adult, GFRalpha1 and Ret were found in the neuropil of enteric ganglia. We conclude that the population of cells expressing the receptors increases during development and persists in the adult, findings that support a neurotrophic role for GDNF in the formation and maintenance of the avian ENS.

Aortic root dilation after the Ross procedure.

This study evaluated changes in neoaortic root geometry in patients who underwent the Ross procedure. Serial postoperative echocardiographic measurements of the neoaortic root indexed to the square root of body surface area (centimeters divided by meters) were obtained from 30 patients (age range 3.1 to 31.4 years) and compared with paired preoperative and immediate postoperative values. Normal aortic root diameter Z scores were derived from root dimensions obtained from 217 healthy controls. Compared with preoperative values, an immediate stretch of the neoaortic versus pulmonary root (annulus and sinuses of valsalva) was observed at a mean follow-up period of 1 week. Additional aortic annular dilation from baseline prehospital discharge values was observed at 2 to 12 months (baseline vs follow-up annulus Z score: 1.4 vs 2.6, p <0.01, n = 16) and at 16 to 33 months follow-up (0.8 vs 2.0, p <0.05, n = 12). In a similar fashion, there was additional enlargement of the aortic sinus from its stretched state at hospital discharge at 2 to 12 months (baseline vs follow-up sinus Z score: 2.0 vs 3.3, p <0.01, n = 17) and at 16 to 33 months (1.7 vs 3.0, p <0.01, n = 13). There were no differences in root size between 2 to 12 and 16 to 33 months after surgery. There was a decrease in left ventricular size with no alteration in blood pressure or degree of aortic valve regurgitation. Thus, aortic root dilation occurs up to the first year after the Ross procedure but does not appear to progress beyond this time.

Defects in embryonic hindbrain development and fetal resorption resulting from vitamin A deficiency in the rat are prevented by feeding pharmacological levels of all-trans-retinoic acid.

Vitamin A is required for reproduction and normal embryonic development. We have determined that all-trans-retinoic acid (atRA) can support development of the mammalian embryo to parturition in vitamin A-deficient (VAD) rats. At embryonic day (E) 0.5, VAD dams were fed purified diets containing either 12 micrograms of atRA per g of diet (230 micrograms per rat per day) or 250 micrograms of atRA per g of diet (4.5 mg per rat per day) or were fed the purified diet supplemented with a source of retinol (100 units of retinyl palmitate per day). An additional group was fed both 250 micrograms of atRA per g of diet in combination with retinyl palmitate. Embryonic survival to E12.5 was similar for all groups. However, embryonic development in the group fed 12 micrograms of atRA per g of diet was grossly abnormal. The most notable defects were in the region of the hindbrain, which included a loss of posterior cranial nerves (IX, X, XI, and XII) and postotic pharyngeal arches as well as the presence of ectopic otic vesicles and a swollen anterior cardinal vein. All embryonic abnormalities at E12.5 were prevented by feeding pharmacological amounts of atRA (250 micrograms/g diet) or by supplementation with retinyl palmitate. Embryos from VAD dams receiving 12 micrograms of atRA per g of diet were resorbed by E18.5, whereas those in the group fed 250 micrograms of atRA per g of diet survived to parturition but died shortly thereafter. Equivalent results were obtained by using commercial grade atRA or atRA that had been purified to eliminate any potential contamination by neutral retinoids, such as retinol. Thus, 250 micrograms of atRA per g of diet fed to VAD dams (approximately 4.5 mg per rat per day) can prevent the death of embryos at midgestation and prevents the early embryonic abnormalities that arise when VAD dams are fed insufficient amounts of atRA.

HERG channel dysfunction in human long QT syndrome. Intracellular transport and functional defects.

Mutations in HERG are associated with human chromosome 7-linked congenital long QT (LQT-2) syndrome. We used electrophysiological, biochemical, and immunohistochemical methods to study the molecular mechanisms of HERG channel dysfunction caused by LQT-2 mutations. Wild type HERG and LQT-2 mutations were studied by stable and transient expression in HEK 293 cells. We found that some mutations (Y611H and V822M) caused defects in biosynthetic processing of HERG channels with the protein retained in the endoplasmic reticulum. Other mutations (I593R and G628S) were processed similarly to wild type HERG protein, but these mutations did not produce functional channels. In contrast, the T474I mutation expressed HERG current but with altered gating properties. These findings suggest that the loss of HERG channel function in LQT-2 mutations is caused by multiple mechanisms including abnormal channel processing, the generation of nonfunctional channels, and altered channel gating.

GDNF is abundant in the adult rat gut.

Glial derived neurotrophic factor (GDNF) is essential for the development of the enteric nervous system (ENS). Although previous work has measured GDNF mRNA levels, little is known about the concentration of GDNF protein produced in developing or adult tissues. The aim of this study was to quantitate the concentration of GDNF protein in various tissues of the developing and adult rat and in adult human gut. A two site antibody immunoassay was used to quantitate GDNF using recombinant rat GDNF as a standard. In the adult rat gastrointestinal tract the intestine contained the highest concentration of GDNF while the stomach and esophagus have the lowest concentrations. The isolated muscular wall of the intestine has approximately four times the GDNF concentration of the intact intestine. Other tissues with smooth muscle such as the aorta and urinary bladder contain moderate GDNF concentrations. In contrast, GDNF is barely detectable in the adult kidney and liver. High concentrations of GDNF were also detected in human colon and jejunum. As development proceeds in the rat, there is a tendency for the concentration of GDNF to increase in the intestine but decrease in other tissues. Treatment of the jejunum with the cationic surfactant benzyldimethyltetradecylammonium chloride (BAC) results in an increase in the number of smooth muscle cells, a decrease in myenteric neurons, and an increase in the concentration of GDNF in homogenates of intestine. The observations that GDNF concentrations are high in the adult intestine suggest that this growth factor may be important for the maintenance of the adult ENS.

Clinical cardiotoxicity following anthracycline treatment for childhood cancer: the Pediatric Oncology Group experience.

PURPOSE: To determine the incidence of clinical cardiotoxicity from anthracycline chemotherapy in children with cancer and to identify associated risk factors. PATIENTS AND METHODS: The study population consisted of 6,493 children with cancer who had received anthracycline chemotherapy on Pediatric Oncology Group (POG) protocols from 1974 to 1990. Cardiotoxicity, defined as congestive heart failure not due to other causes, abnormal measurements of cardiac function that prompted discontinuation of therapy, or sudden death from presumed cardiac causes, was determined by a review of protocol records. RESULTS: Cardiotoxicity was confirmed in 106 patients (1.6%): 58 had congestive heart failure, 43 had changes in measures of cardiac function that prompted the discontinuation of therapy, and five died suddenly from presumed cardiac causes. In a multivariate analysis, factors that contributed to the relative risk (RR) of toxicity were a cumulative anthracycline dose > or = 550 mg/m2 of body-surface area (RR = 5.2), maximal dose > or = 50 mg/m2 (RR = 2.8), female sex (RR = 1.9), black race (RR = 1.7), presence of trisomy 21 (RR = 3.4), and exposure to amsacrine (RR = 2.6). Cardiotoxicity within 1 year after the completion of anthracycline treatment (early cardiotoxicity) represented 89.5% of all cases. CONCLUSION: Early clinical cardiotoxicity in children treated with anthracycline is rare. A high maximal dose, or cumulative dose of anthracycline, female sex, black race, presence of trisomy 21, and treatment with amsacrine increase the risk for anthracycline-associated cardiotoxicity.

Enhanced resting left ventricular filling in patients with successful coarctation repair and exercise-induced hypertension.

M-mode and Doppler echocardiographic analyses of left ventricular (LV) shortening and filling were performed in 50 patients who underwent coarctectomy (median follow-up 9.5 years) and in 16 athletes in a control group before an exercise stress test with upright bicycle ergometry was performed. Thirty-two of 50 patients and 18 of 50 patients had a normotensive and hypertensive response to exercise, respectively. Preexercise echocardiographic data were compared among the control, normotensive, and hypertensive patient groups. LV peak filling rates (dD/dt, diastole) were increased in the hypertensive group (18.3 +/- 3.5) compared with those in the normotensive group (14.4 +/- 3.2; p < 0.001) and the control group (13.6 +/- 2.8; p < 0.001). LV shortening was enhanced in the coarctectomy group compared with that in the control group. A higher aortic isthmus Doppler gradient at peak exercise was not found in the hypertensive group compared with that in the normotensive group. Therefore patients with successful coarctectomy in childhood have enhanced LV shortening and relaxation at rest. Demonstration of enhanced LV peak filling rates may help identify patients at risk for exercise-induced hypertension.

Appearance of neurons in the developing chick gut.

The enteric nervous system is formed from neural crest-derived cells. These cells enter the gut, migrate, proliferate, and ultimately differentiate into neurons and glia. We have used a human anti-neuronal autoantibody (ANNA-1), which recognizes neuron-specific RNA-binding proteins of the Hu family as an early marker of neuronal phenotype, to study the appearance of enteric neurons in the developing chicken gut. Immunoreactive cells appear first in the gizzard primordium at E3.5 and are found at progressively more caudal locations in the gut as development proceeds. Nascent neurons are present at the yolk stalk at E4.5, at the ileocecal junction at E6.5, and within the rectum at E7.5-8.5. Neurons appear slightly later in the esophagus. Aggregates of cells resembling developing ganglia were first observed at E6.5 in the distal esophagus and at E8.5 in the proximal esophagus. A small number of cells appeared in the vagus nerve trunks at E4.5 and that number increased at E7.5-8.5. Immunoreactive cells were also found in the sympatho-aortic plexus between the mesonephri and in the dorsal mesentery. These cells appeared to coalesce and form the ganglionated Nerve of Remak which contained positive cells at E3.5. This Nerve extended to the yolk stalk at E4.5 and to duodenum at E6.5. We conclude that the appearance of nascent neurons occurs first in the gizzard and proceeds more rapidly in a distal than proximal direction along the gut. Furthermore, cell that appear to be nascent neurons are found in the vagus and in the dorsal mesentery.

Maturational differences in coronary flow and interstitial transudate adenosine during alteration of perfusate oxygenation in isolated rabbit hearts.

This study was designed to investigate effects of perfusate oxygenation and maturation on coronary flow (CF), interstitial transudate adenosine (ITA) and coronary effluent adenosine (CEA) in isolated rabbit hearts. Hearts were paced at a fixed rate and were perfused under constant pressure at two different levels of perfusate oxygenation: baseline (B) (pO2 = 408 +/- 7 mmHg, O2 content = 1.28 +/- 0.03 ml O2/dl) and a lower level (L) (pO2 = 189 +/- 4 mmHg, O2 content = 0.59 +/- 0.02 ml O2/dl). CF was higher in immature (I, age 5 weeks) compared with mature (M, age 12 weeks) hearts at both levels of perfusate oxygenation (9.7 +/- 0.4 vs. 7.7 +/- 0.3 and 12.9 +/- 0.4 vs. 9.2 +/- 0.3 ml/min/g). I hearts had correspondingly higher values for myocardial oxygen consumption (MVO2) (53 +/- 3 vs. 49 +/- 2 and 39 +/- 3 vs. 35 +/- 2 microL O2/min/g), but similar values for venous oxygen tensions (nuO2) (240 +/- 9 vs. 219 +/- 10 and 74 +/- 4 vs. 62 +/- 3 mmHg), compared with M hearts at B and L. Although interstitial transudate adenosine (ITA) concentration was similar in I and M hearts at B (409 +/- 75 vs. 254 +/- 39 nM), it was lower in I than M hearts at L (2500 +/- 770 vs. 4210 +/- 1000 nM).(ABSTRACT TRUNCATED AT 250 WORDS)