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Biomedical subjects

J Ye

Publications and source records attributed to J Ye.

At least 217 records · Page 12Linked to original sources
PubMed1996

Neuronal damage after hypothermic circulatory arrest and retrograde cerebral perfusion in the pig.

BACKGROUND: Antegrade and retrograde cerebral perfusion during hypothermic circulatory arrest (HCA) has been reported to provide better brain protection during operation than hypothermic circulatory arrest alone. However, the efficacy of these techniques remains to be fully determined, especially when used for prolonged periods. We used a pig model to evaluate the histopathologic consequences of HCA and the potential benefit of cerebral perfusion during HCA. METHODS: Twenty-two pigs were divided into four groups and exposed to either anesthesia alone, 120 minutes of HCA (15 degrees C), 120 minutes of retrograde cerebral perfusion at 15 degrees C during HCA, or 120 minutes of antegrade cerebral perfusion at 15 degrees C during HCA, and then reperfused for 60 minutes under cardiopulmonary bypass at 37 degrees C. The brains were perfusion fixed at the end of the experiments and examined by light microscopy. RESULTS: There were no morphologic changes in any areas of the brains in the anesthesia group, and very minor changes in some areas of the brains in the antegrade cerebral perfusion. group. Varying severity of neuronal damage was found in the brains of all the pigs in the HCA and retrograde cerebral perfusion groups. The severity of ischemic damage in the brain showed the following descending order: hippocampus (CA4), caudate nucleus, cerebral cortex, putamen, thalamus, Purkinje cells of the cerebellum, pons, and mesencephalic gray matter. In the hippocampus the order of damage was CA4, CA3, polymorphous layer of the dentate gyrus, prosubiculum, CA2, CA1, and granule cell layer of the dentate gyrus. The damage in the retrograde cerebral perfusion group was less severe relative to the HCA group in many areas (no significance except mesencephalic gray matter). CONCLUSIONS: These results demonstrate that the pattern of neuronal damage in pigs subjected to HCA and retrograde cerebral perfusion differs from the traditional pattern in that the caudate nucleus and hippocampal CA4 region are the most vulnerable to ischemia-hypoxia. Our results also suggest that antegrade cerebral perfusion prevented ischemic damage to the brain and retrograde cerebral perfusion provided some protection but moderately severe damage occurred.

Animals↗
PubMed1996

Cerebral protection during moderate hypothermic circulatory arrest: histopathology and magnetic resonance spectroscopy of brain energetics and intracellular pH in pigs.

OBJECTIVE: We evaluated the effect of antegrade and retrograde brain perfusion during moderate hypothermic circulatory arrest at 28 degrees C. METHODS: Phosphorus 31-magnetic resonance spectroscopy was used to follow brain energy metabolites and intracellular pH in pigs during 2 hours of ischemia and 1 hour of reperfusion. Histopathologic analysis of brain tissue fixed at the end of the experimental protocol was performed. Fourteen pigs were divided into two experimental groups subjected to antegrade (n = 6) or retrograde (n = 8) brain perfusion. Anesthesia (n = 8) and hypothermic cardiopulmonary bypass groups (15 degrees C, n = 8) served as control subjects. In the antegrade and retrograde brain perfusion groups, the initial bypass flow rate was 60 to 100 ml x kg(-1) x min(-1). In the antegrade group, the brain was perfused through the carotid arteries at a flow rate of 180 to 210 ml x min(-1) during circulatory arrest at 28 degrees C. In the retrograde group, the brain was perfused through the superior vena cava at a flow rate of 300 to 500 ml x min(-1) during circulatory arrest at 28 degrees C. RESULTS: The intracellular pH was 7.1 +/- 0.1 and 7.2 +/- 0.1 in the anesthesia and hypothermic bypass groups, respectively. Brain intracellular pH and high-energy metabolites (adenosine triphosphate, phosphocreatine) did not change during the course of the 3.5-hour study. In the antegrade group, adenosine triphosphate and intracellular pH were unchanged throughout the protocol. In the retrograde perfusion group, the intracellular pH level decreased to 6.4 +/- 0.1, and adenosine triphosphate and phosphocreatine levels decreased within the first 30 minutes of circulatory arrest and remained at low levels until the end of reperfusion. High-energy phosphates did not return to their initial levels during reperfusion. Histopathologic analysis of nine regions of the brain showed good preservation of cell structure in the anesthesia, hypothermic bypass, and antegrade perfusion groups. The retrograde perfusion group showed changes in all the regions examined. CONCLUSIONS: The study shows that moderate hypothermic circulatory arrest at 28 degrees C with antegrade brain perfusion during circulatory arrest protects the brain but that retrograde cerebral perfusion at 28 degrees C does not protect the brain.

Adenosine Triphosphate↗
PubMed1996

The inversion of the exponential Radon transform for quantitative brain SPECT.

The mathematical derivation for the inversion of the exponential Radon transform is presented and the implementation of the inversion is detailed. The inversion can be verified and implemented by the readers for practical applications, such as for quantitative reconstruction of brain SPECT (single-photon emission computed tomography).

Brain↗
PubMed1996

Cloning, sequencing, and analysis of aklaviketone reductase from Streptomyces sp. strain C5.

DNA sequence analysis of a region of the Streptomyces sp. strain C5 daunomycin biosynthesis gene cluster, located just upstream of the daunomycin polyketide biosynthesis genes, revealed the presence of six complete genes. The two genes reading right to left include genes encoding the potentially translationally coupled gene products, an acyl carrier protein and a ketoreductase, and the four genes reading divergently, left to right, include two open reading frames of unknown function followed by a gene encoding an apparent glycosyltransferase and dauE, encoding aklaviketone reductase. Extracts of Streptomyces lividans TK24 containing recombinant DauE catalyzed the NADPH-specific conversion of aklaviketone, maggiemycin, and 7-oxodaunomycinone to aklavinone, epsilon-rhodomycinone, and daunomycinone, respectively. Neither the product of dauB nor that of the ketoreductase gene directly downstream of the acyl carrier protein gene demonstrated aklaviketone reductase activity.

Amino Acid Sequence↗
PubMed1996

Characterization of the human granulocyte-macrophage colony-stimulating factor gene promoter: an AP1 complex and an Sp1-related complex transactivate the promoter activity that is suppressed by a YY1 complex.

It is well documented that a repeated CATT element in the human granulocyte-macrophage colony-stimulating factor (GM-CSF) gene promoter is required for promoter activity. However, the transcription factors that are able to transactivate this enhancer element remain unidentified. Recently, we have found that nuclear factor YY1 can interact with the enhancer element. Here, we report that in addition to YY1, two other nuclear factors have been identified in the DNA-protein complexes formed by the CATT oligonucleotide and the Jurkat T-cell nuclear protein. One of these factors is AP1, and the other one is an Sp1-related protein. Results from transient transfection of Jurkat T cells have revealed that formation of both AP1 and the Sp1-related complex is required for the full enhancer activity of the CATT element. This result is supported by cotransfection of a c-jun expression vector and mutational analysis of the AP1 site or the Sp1-related protein binding site. In contrast, formation of the YY1 complex suppresses enhancer activity, since deletion of the YY1 complex induces an augmentation of the enhancer activity and overexpression of YY1 results in an attenuation of the enhancer activity. Results from the mechanism study have revealed that YY1 is able to inhibit transactivation mediated by either AP1 or the Sp1-related protein, and YY1 suppressive activity is DNA binding dependent. Taken together, these data support the ideas that AP1 and the Sp1-related nuclear protein are required for transactivation of the human GM-CSF gene promoter and that YY1 can suppress transactivation of the promoter even under inducible conditions.

Base Sequence↗
PubMed1996

Sp1 binding plays a critical role in Erb-B2- and v-ras-mediated downregulation of alpha2-integrin expression in human mammary epithelial cells.

The human alpha2-integrin gene is transcriptionally downregulated in a nontumorigenic human mammary epithelial cell line, MTSV1-7, and its clonal variant HB2, overexpressing the Erb-B2 oncogene. In this study, we have used deletion mutations within the alpha2-integrin promoter inserted 5' of the chloramphenicol acetyltransferase or luciferase reporter genes to identify the element that is responsible for the Erb-B2-mediated downregulation. The results of the transient-transfection assay showed that the Sp1 binding element located in the core region (positions --64 to +1) of the alpha2-integrin promoter plays an essential role in the alpha2-integrin promoter activity and its downregulation by Erb-B2. By gel shift assay, we have demonstrated that this element binds with a high degree of affinity not only to Sp1, but also to Sp3. The downregulation of the alpha2-integrin promoter activity could also be achieved by overexpression of v-Hras (v-ras), suggesting that the signals generated by Erb-B2, which lead to downregulation of the alpha2-integrin gene expression, may proceed through the ras pathway. Both the Erb-B2- and the v-ras-overexpressing cells exhibited a Sp1 DNA binding activity lower than that of the parental line, while the relative levels of Sp1 protein in these cells were not altered. The Erb-B2- and v-ras-mediated downregulation could be reversed by the overexpression of Sp1 and by a dominant negative variant of ras (rasN17), confirming the importance of Sp1 and the ras pathway. The inhibitory effects of Erb-B2 on transcriptional activity of the alpha2-integrin promoter were observed in transient-cotransfection assays using alpha2-integrin reporter plasmids and plasmids expressing the Erb-B2 or v-ras oncogene. The same effects were seen when an alpha2-integrin reporter gene construct was transfected into MTSV1-7 or HB2 cells permanently overexpressing Erb-B2 or v-ras. The effects of Erb-B2 or v-ras on the transcriptional activity of the alpha2-integrin promoter were observed in nontumorigenic luminal epithelial cell lines (MTSV1-7 and HB2) as well as in the breast cancer cell line T47D. These data suggest that in luminal epithelial cells and the breast cancers which develop from them, the Erb-B2 proto-oncogene signaling leads to inhibition of (alpha)2(beta)1-integrin gene expression and could contribute to the disruption of tissue architecture seen in breast cancers.

Antigens, CD↗
PubMed1996

The nuclear factor YY1 suppresses the human gamma interferon promoter through two mechanisms: inhibition of AP1 binding and activation of a silencer element.

Our group has previously reported that the nuclear factor Yin-Yang 1 (YY1), a ubiquitous DNA-binding protein, is able to interact with a silencer element (BE) in the gamma interferon (IFN-gamma) promoter region. In this study, we demonstrated that YY1 can directly inhibit the activity of the IFN-gamma promoter by interacting with multiple sites in the promoter. In cotransfection assays, a YY1 expression vector significantly inhibited IFN-gamma promoter activity. Mutation of the YY1 binding site in the native IFN-gamma promoter was associated with an increase in the IFN-gamma promoter activity. Analysis of the DNA sequences of the IFN-gamma promoter revealed a second functional YY1 binding site (BED) that overlaps with an AP1 binding site. In this element, AP1 enhancer activity was suppressed by YY1. Since the nuclear level of YY1 does not change upon cell activation, our data support a model that the nuclear factor YY1 acts to suppress basal IFN-gamma transcription by interacting with the promoter at multiple DNA binding sites. This repression can occur through two mechanisms: (i) cooperation with an as-yet-unidentified AP2-like repressor protein and (ii) competition for DNA binding with the transactivating factor AP1.

Base Sequence↗
PubMed1996

Surgical treatment of bone tumors in conjunction with microwave-induced hyperthermia and adjuvant immunotherapy. A preliminary report.

OBJECTIVE: To develop an alternative approach in conjunction with microwave-induced hyperthermia. PATIENTS AND METHODS: Thermotherapy with microwave intracorporeal irradiation was used to treat 73 patients with bone tumors. The series was composed of 58 patients with malignant tumors and 15 with benign tumors: most of tumors occurred about knee joints (53/73 = 72.6%). The surgical procedure included separating the tumor bearing segment from surrounding normal tissues with a safe margin, cooling the normal tissues including the neurovascular bundle and the intraarticular structures with a water circulation system, while heating the tumor with the antenna array of a microwave system and providing an adequate soft-tissue cover for the dead bone. Postoperatively, an immune therapy regimen was carried out regularly. The patients' immunologic functions were monitored by assay of the subpopulation of T cells, IL-2 and sIL-2 R (soluble IL-2 receptor). RESULTS: Follow-up varied from 3 to 38 months (mean 19 months). Excluding 3 patients with malignancy in the vertebrae treated for palliation, 70 were evaluated according to oncological and orthopedic criteria. Five patients had local recurrence and required amputation. The remaining 65 had excellent local control. In 6 of the 55 patients with malignancy of the extremities, lung metastasis occurred one to two years after surgery. The oncological results were similar to those obtained by other limb-saving procedures. Pathological fracture occurred at devitalized bone in 5 patients. In 72.5% of the patients (29 of 40 tumor-free cases followed more than one year), knee joints functioned well, being stable and painless with almost full range of motion. Single photon emission computered tomography (SPECT) for 16 patients revealed revascularization of the devitalized tumor bearing bone segment could accomplish in one year or more. The immune states were improved in various extends after thermotherapy plus immunotherapy in the majority of patients. CONCLUSION: These results show that the use of microwave hyperthermia and adjuvant immunotherapy in conjunction with the surgical treatment of bone tumors can be considered a definitive procedure, which is safe and well-tolerated. The oncological and orthopedic results are encouraging.

Adolescent↗
PubMed1995

Gradual loss of T-helper 1 populations in spleen of mice during progressive tumor growth.

BACKGROUND: The carefully orchestrated events that result in a protective immune response are coordinated to a large extent by cytokines produced by T helper 1 (Th1) and T helper 2 (Th2) T-cell subsets, which are two arms of the immune system. Th1 cells preferentially produce interleukin 2 (IL-2), interferon gamma (IFN gamma), and tumor necrosis factor (TNF), resulting in a cellular response that helps to eliminate infected cells. In contrast, Th2 cells produce IL-4, IL-5, IL-6, and IL-10 and stimulate an antibody response that helps to prevent the cells from becoming infected. The clinical progression of several infectious diseases, including human immunodeficiency virus, some types of parasitoses, and tuberculosis, is thought to be associated with the predominance of a Th2-type T-cell response. Recent reports have demonstrated the presence of T cells producing Th2 lymphokines (IL-4, IL-6, and IL-10) in tumor-infiltrating lymphocytes of renal cell carcinoma. PURPOSE: The purpose of this study was to investigate at the molecular level whether there was any change in the splenic T cells of mice with progressively growing tumors from a Th1 to a Th2 DNA-binding pattern or phenotype. METHODS: Splenic T cells from mice bearing renal cell carcinoma or MCA-38 colon carcinoma were tested for cytokine production after in vitro activation. Nuclear extracts of splenic T cells were used for the DNA-binding assay using IFN-gamma core promoter region, the kappa B (kappa B) site from immunoglobulin gene, and the nuclear factor of activated T-cell (NFAT) site from IL-2 gene. RESULTS: Splenic T cells from mice bearing renal cell carcinoma or MCA-38 colon carcinoma preferentially produced Th2 cytokines (i.e., IL-4) upon activation and showed a marked decrease in Th1 cytokine (particularly IFN gamma) production compared with the production observed in normal splenic T cells. The DNA-binding assay with the IFN-gamma core promoter region confirmed the gradual decline in the nuclear transcription factors associated with the Th1 phenotype during tumor progression in both tumor models. Renal cell carcinoma-bearing mice, successfully treated with flavone-8-acetic acid and recombinant human IL-2, showed a reversion to a Th1-like pattern. In addition, nuclear extracts of T cells from tumor-bearing animals showed a Th2-type kappa B-binding pattern. Moreover, the NFAT complex present in the normal splenic T cells was lost at the later stages of tumor progression; instead, a new complex was present in mice bearing long-term tumors. CONCLUSION: T cells from tumor-bearing mice lose the Th1 phenotype with progressive tumor growth.

Animals↗
PubMed1995

Gene structure and amino acid sequence of the human cone photoreceptor cGMP-phosphodiesterase alpha' subunit (PDEA2) and its chromosomal localization to 10q24.

The genomic organization and nucleotide structure of the human cone photoreceptor cGMP phosphodiesterase alpha'-subunit (alpha'-PDE) gene (PDEA2) as well as its chromosomal localization have been determined. This gene, which spans about 48 kb, consists of 22 exons and codes for an 858-amino-acid protein. The alpha'-PDE gene maps to human chromosome 10q24. Its coding region shows about 90% nucleotide identity and 93% amino acid identity with the corresponding region of the bovine gene. The intron-exon organization of the genes encoding human cone alpha'-PDE and rod beta-PDE are very similar, suggesting that these proteins have a close phylogenetic relationship and probably a common origin.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMed1995

Negative transcriptional regulation of the interferon-gamma promoter by glucocorticoids and dominant negative mutants of c-Jun.

Interferon-gamma (IFN-gamma) is an immunoregulatory cytokine expressed in large granular lymphocytes and T cells. However, the molecular mechanisms underlying IFN-gamma gene transcription have not been fully defined. Here, we analyze the mechanisms responsible for the inhibition of IFN-gamma promoter activity by the glucocorticoid hormone dexamethasone. Cotransfection assays performed in Jurkat T cells demonstrated that the activity of the initial 108 base pairs of the IFN-gamma promoter was down-regulated in the presence of dexamethasone. Furthermore, utilizing electrophoretic mobility shift analysis, we identified activator protein 1 AP-1-cAMP response element binding protein-activating transcription factor (CREB-ATF) binding elements situated in positions of the IFN-gamma promoter previously identified as essential for promoter activity. Moreover, dominant negative mutants of the c-Jun proto-oncogene were able to mimic the same down-regulatory effect exerted by dexamethasone, and mutations that abolished the binding of the AP-1 CREB-ATF factors were able to block the glucocorticoid effect. These results suggest a model involving the inhibition of IFN-gamma AP-1 CREB-ATF DNA binding complexes as one of the mechanisms involved in the negative regulatory action of glucocorticoids on IFN-gamma gene expression and support the relevance of AP-1 CREB-ATF binding factors during the transcriptional activation of the IFN-gamma promoter in T cells.

Base Sequence↗
PubMed1995

Factor Xa-factor Va complex assembles in two dimensions with unexpectedly high affinity: an experimental and theoretical approach.

The influence of phospholipid vesicle concentration and size on the affinity and the kinetics of assembly of the prothrombin activation complex are examined. Activation of prethrombin 1 was used to monitor complex formation between factors Va and Xa. When activation rates were measured immediately after the addition of the reactants, the rate of activation increased, and subsequently decreased, as a function of increasing vesicle concentration. Larger vesicles did not inhibit the reaction to a comparable extent until much higher phospholipid concentrations were present. The inhibition by high vesicle concentrations was significantly reduced by a prolonged incubation period. These results are interpreted as an initial step of factors Va and Xa binding independently to separate phospholipid vesicles, followed by a slow redistribution between vesicles to maximize complex formation. These experiments indicated that the Kd < or = 25 pM, much tighter than previously reported. Two-dimensional binding on the membrane surface was investigated under conditions where all of the proteins were membrane bound. The complex formation was independent of the surface density of the reactions, indicating a near complete complex formation at the lowest surface density of the reactants. Thus, we conclude that (i) the overall affinity of factor Va-factor Xa interaction in the presence of vesicles is higher than previously appreciated, and (ii) factor Va and factor Xa complex once they bind to the same vesicle.

Animals↗
PubMed1995

The majority of murine VH12-expressing B cells are excluded from the peripheral repertoire in adults.

We have previously demonstrated that at birth most productive (P) VH12 rearrangements in B10.H-2aH-4bp/Wts (2a4b) mice encode a ten-amino acid CDR3, and that a significant fraction of the expected repertoire is absent. We have now examined the adult VH12 CDR3 repertoire involving all four JH gene segments in both peritoneum and spleen. Of the 74 P VH12 rearrangements from these tissues 67 encode a CDR3 of ten amino acids and include a Gly in the fourth position (designated 10/G4). Most of these rearrangements appear to derive from phosphatidylcholine (PtC)-specific B cells, which also have a 10/G4 VHCDR3, since few 10/G4 P rearrangements were present in spleen cells depleted of PtC-specific B cells. Thus, the VH12 B cell repertoire in adult mice is largely restricted to the use of a single CDR3 motif and to a single antigen specificity. This bias results from two selection events: (1) selective exclusion of most VH12 B cells from the peripheral repertoire, and (2) clonal expansion in the periphery of VH12 B cells that have a 10/G4 VHCDR3 and bind PtC. Analysis of VH12-JH1 rearrangements in viable motheaten (mev/mev) mice, which have an abnormal B cell repertoire due to a defective phosphatase (Hcph) and have barely detectable numbers of PtC-specific B cells, indicates that selective exclusion of VH12 B cells from the peripheral repertoire occurs normally, but that clonal expansion of 10/G4 VH12 B cells is minimal. This is evidence that the selective exclusion of VH12 B cells from the peripheral repertoire and the clonal expansion of VH12 B cells with a 10/G4 CDR3 are due to independent signaling events.

Age Factors↗
PubMed1995

Cellular and molecular mechanisms of IFN-gamma production induced by IL-2 and IL-12 in a human NK cell line.

Interferon-gamma (IFN-gamma) is an important immunoregulatory protein produced predominantly by T cells and large granular lymphocytes (LGL) in response to different extracellular signals. In particular, two interleukins (ILs), IL-2 and IL-12, have been shown to be potent inducers of IFN-gamma gene expression in both T cells and LGL. Although it has been reported that there are some T cell lines that produce IFN-gamma in response to IL-2 and IL-12 stimulation, there has as yet been no report of a natural killer (NK) cell line that responds in a similar manner. In this report we present evidence that the cell line NK3.3 derived from human NK cells, responds to both IL-2 and IL-12, as measured by increases in IFN-gamma and granulocyte-macrophage colony-stimulating factor (GM-CSF) cytoplasmic mRNA and protein expression. In addition, when used together IL-2 and IL-12 synergized in the induction of IFN-gamma and GM-CSF and this synergy was attributed to an increased accumulation and stability of the IFN-gamma and GM-CSF mRNAs. To investigate the signaling pathways involved in the gene induction, five inhibitors, cyclosporin A (CsA), transforming growth factor-beta, cycloheximide, genistein, and staurosporine A, were used in analyzing the effects of IL-2 and IL-12 on NK3.3 cells. The results suggest that activation of protein kinase C, but not new protein synthesis, is required for IL-2 induction of IFN-gamma and GM-CSF cytoplasmic mRNA. In contrast, IL-12 induction of IFN-gamma cytoplasmic mRNA appears to only partially depend on activation of protein kinase C. Furthermore, both transforming growth factor-beta and genistein, a tyrosine kinase inhibitor, could suppress IL-2 and IL-12 signaling but CsA was generally inactive. It also was observed that suppression of cytokine gene expression by these agents was independent of the inhibition of proliferation. In addition, IL-2 but not IL-12 induced nuclear factors NF-kappa B and AP1, and regulation of the nuclear levels of these two DNA binding protein complexes is correlated with IFN-gamma and GM-CSF gene expression. These data indicate that IL-2 and IL-12 may have distinct signaling pathways leading to the induction of IFN-gamma and GM-CSF gene expression, and that the NK3.3 cell line may serve as a novel model for dissecting the biochemical and molecular events involved in these pathways.

Alkaloids↗
PubMed1995

beta-Galactosidase transgene expression in transplanted rabbit retinal pigment epithelial cells in vivo.

BACKGROUND: Intraocular transplantation of genetically modified cells that release a particular substance could have a major impact on the treatment of various ocular diseases. We studied the expression of the reporter gene beta-galactosidase (lacZ) in transplanted retinal pigment epithelial (RPE) cells in vivo. METHODS: RPE cells from pigmented rabbits were transduced with the beta-galactosidase gene in a retroviral vector. Cells were then assayed for gene expression and transplanted subretinally into the eyes of New Zealand White rabbits. RPE cells that were transduced with a similar vector without the beta-galactosidase gene were used as controls. Rabbits were killed on days 1, 7, and 21 and the eyes processed for transmission electron microscopy RESULTS: Neomycin-resistant rabbit RPE cells that showed beta-galactosidase activity were generated within 2-5 weeks. After transplantation, viable RPE cells that expressed the transgene and that phagocytosed rod outer segments were observed on days 1, 7, and 21 CONCLUSIONS: The results show that generation of genetically modified RPE cells is feasible and that the transplanted cells remain viable and continue to express the transgene in the subretinal space of the host animal for at least 21 days. Transplantation of such genetically modified RPE cells could provide a new tool for studying retinal diseases and, potentially, for correcting metabolic abnormalities in retinal degenerations and dystrophies.

3T3 Cells↗
PubMed1995

Antegrade and retrograde continuous warm blood cardioplegia: a 31P magnetic resonance study.

BACKGROUND: Retrograde normothermic blood cardioplegia has been shown to provide myocardial protection during certain bypass procedures. However, a number of animal studies have shown less than optimal myocardial protection with this technique. METHODS: Isolated, beating porcine hearts were perfused antegradely (aortic root pressure = 75 to 95 mm Hg) for 30 minutes. Arrest was induced and maintained for 60 minutes with high K+ blood cardioplegia delivered either antegradely (n = 8) or retrogradely (n = 8) (coronary sinus pressure = 35 to 55 mm Hg). Perfusate was switched to normokalemic blood for recovery of sinus rhythm (30 minutes). Intracellular pH, creatine phosphate, inorganic phosphate, and adenosine triphosphate were monitored continuously and noninvasively with phosphorus 31 magnetic resonance spectroscopy throughout the experiment, and functional variables (rate-pressure product and the positive and negative first derivatives of left ventricular pressure) were assessed concurrently. RESULTS: Antegrade cardioplegia maintained high-energy metabolites, intracellular pH, and myocardial function. Retrograde normothermic blood cardioplegia resulted in an increase in inorganic phosphate (197% +/- 15% of control) and a decrease in creatine phosphate (51% +/- 6% of control). There was no significant difference in myocardial function between the two groups (p > 0.05). The magnetic resonance spectroscopy data indicate ischemia occurred within 2 minutes of the initiation of retrograde perfusion. CONCLUSIONS: This study suggests that retrograde normothermic blood cardioplegia causes a transition of the myocardium to ischemic metabolism in the normal porcine heart.

Adenosine Triphosphate↗