ISSN:0009-7330    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

Familial hypertrophic cardiomyopathy (FHC) is characterized by idiopathic myocardial hypertrophy, which often and predominantly involves the interventricular septum. The disease is transmitted as an autosomal dominant trait, and its major risk is sudden death. It was recently demonstrated that this disease is genetically heterogeneous and that in 13 of 18 unrelated families the morbid locus, termed FHC-1, maps to chromosome 14q11–12 in and/or very near the cardiac β-myosin heavy chain gene. We have performed linkage analysis with five chromosomal markers detecting polymorphisms in either the cardiac β-myosin heavy chain gene or the cardiac actin gene (located on chromosome 15q) on eight families from different regions of France. We show that 1) it is possible to analyze medium-sized families by using highly informative microsatellite markers located in these genes and 2) the disease is not linked to the two contractile protein genes in any of these families. Moreover, 10–20% of chromosome 14 and 20–40% of chromosome 15 in the vicinity of the respective markers were excluded as possible locations for the morbid locus. These results provide new insights into the identification of the genes responsible for FHC.

ISSN:0009-7330    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

Brain natriuretic peptide (BNP) and C-type natriuretic peptide (CNP) are novel natriuretic peptides, originally isolated from porcine brain. Similar to atrial natriuretic peptide (ANP), BNP is also synthesized in and secreted from cardiocytes, but CNP is not expressed at significant levels in normal adult myocardium. Previous studies have indicated that the serum level and ventricular expression of the ANP gene were augmented in patients with heart failure. Recently, the serum level of BNP was also reported to increase in human heart failure. To examine whether or not the expression of these natriuretic peptides is regulated in ventricular myocardium in a concordant manner, we performed Northern blot analysis using total cellular RNA isolated from the diseased left ventricles of 30 cardiac transplant recipients with end-stage heart failure, seven ventricles from organ donors (control group), and two ventricles of artificially aborted 17- and 19-week-old fetuses. The levels of mRNAs encoding both BNP and ANP increased significantly (p<0.01) in the left ventricular myocardium from the patients with end-stage heart failure as compared with the control group. The levels of BNP mRNA correlated positively with those of ANP mRNA (r=0.73,p<0.01) and negatively with those of sarcoplasmic reticulum Ca2+-ATPase mRNA (r=-0.66,p<0.01) in the left ventricular myocardium from the patients with heart failure. There was also a negative correlation between the levels of ANP and the sarcoplasmic reticulum Ca2+-ATPase mRNAs (r= −0.65,p<0.01). In fetal myocardium, ventricular expression of ANP mRNA was higher and that of BNP mRNA was unchanged as compared with adult control myocardium. In contrast, CNP mRNA was not detectable by Northern blot analysis in either the normal, fetal, or diseased ventricular myocardium. These data suggest that ventricular expression of BNP and ANP mRNAs is concordantly regulated in patients with end-stage heart failure and that this coexpression of these two natriuretic peptides may play an important role in a compensatory process in human heart failure. In contrast, expression of BNP and ANP is discordantly regulated in the fetal ventricles, and CNP is probably never expressed at the significant level detectable by Northern blot analysis in the ventricles either during development or in disease states.

ISSN:0009-7330    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

The molecular basis for the systolic and diastolic dysfunction characteristic of end-stage heart failure in humans remains poorly understood. It has been proposed that both abnormal calcium handling and defects in the contractile apparatus may contribute to the myocardial dysfunction. Two channels, the calcium release channel (CRC) or ryanodine receptor of the sarcoplasmic reticulum (SR), and the slow calcium channel or dihydropyridine receptor (DHPR) of the transverse tubule, play key roles in regulating intracellular calcium concentration and in excitation-contraction (E-C) coupling in the heart. The DHPR serves as the voltage sensor and plasma membrane calcium channel resulting in activation of the CRC during E-C coupling in heart muscle. In this study, we investigated the levels of CRC expression in several forms of end-stage heart failure in humans. A cardiac CRC cDNA was cloned from rabbit and used as a probe for Northern blot analyses to determine mRNA levels in the left ventricles of normal (n=4) and cardiomyopathic (n=34) human hearts from patients undergoing cardiac transplantation. Compared with normal patients, patients with ischemic cardiomyopathy (n=18) showed a 28% decrease in CRC mRNA levels (p<0.025) and patients with idiopathic dilated cardiomyopathy (n=14) a nonsignificant 12% increase. In these same hearts, α-actin levels were unchanged in end-stage heart failure, as has been previously reported. This is the first report indicating that the expression of the CRC mRNA is abnormal in end-stage human heart failure. The decreased expression of the CRC found specifically in patients with ischemic myopathy (but not idiopathic dilated cardiomyopathy) may, in part, explain differences in calcium handling and response to therapy observed among patients with different forms of cardiomyopathy. Decreased CRC expression could be related to abnormal contractile function in cardiomyopathic muscle resulting from ischemic insult.

ISSN:0009-7330    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

Genetic manipulation of the vasculature may offer insights into the pathogenesis of coronary artery disease and may lead to gene therapy for disorders such as restenosis after percutaneous coronary angioplasty. The goal of this study was to develop a percutaneous method for gene transfer into coronary arteries of intact animals. Liposomes were used to facilitate transfection in coronary arteries with a plasmid containing the cDNA encoding luciferase. This reporter was chosen since it is not expressed in mammalian cells, and it can be quantified using a sensitive assay (light production). Mongrel dogs were catheterized, and DNA was delivered to coronary arteries via a porous perfusion balloon system. Luciferase expression was measured 3–5 days after the procedure, when the dogs were killed. Luciferase activity in control arteries (n=12) was no higher than average background activity. Eight of 12 transfected arteries exhibited gene expression, averaging 4.3±2.1 pg luciferase (p<0.01, transfected versus control arteries). In addition, the ability to transfect DNA into femoral arteries without a transfection vehicle was tested. Five dogs were subjected to surgical transfection attempts in their femoral arteries with either DNA alone or DNA plus liposomes. Luciferase was expressed in all 10 femoral arteries; those treated with DNA alone expressed 35.6±8 pg luciferase, and those treated with DNA plus liposomes expressed 42.3±14 pg luciferase (p=0.70). These results demonstrate the use of a percutaneous catheter to achieve gene transfer and expression in coronary arteries of intact dogs and suggest that the efficiency of intra-arterial gene transfer may be similar whether or not a transfection vehicle is used.

ISSN:0009-7330    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

To elucidate the physiological and pathophysiological roles of the natriuretic peptide family in vascular smooth muscle cells, in which the natriuretic peptide family is implicated in growth inhibition as well as vasorelaxation, we have examined the phenotype-related expression of three kinds of natriuretic peptide receptors in rat aortic smooth muscle cells. The expression of natriuretic peptide receptors at the mRNA level was studied by Northern blot hybridization, and the expression at the protein level was determined by the cGMP production method and receptor binding assay. In intact aortic media, atrial natriuretic peptide (ANP)-A receptor mRNA and ANP-B receptor mRNA were detected, and the potency of cGMP production by ANP was at least two orders of magnitude stronger than that by C-type natriuretic peptide. Clearance receptor mRNA was undetectable, and only a small amount of the clearance receptor was detected by the binding assay in intact aortic media. By contrast, in cultured aortic smooth muscle cells at the first, fifth, and 17th passages, the ANP-B receptor mRNA level markedly increased; meanwhile, the expression of the ANP-A receptor mRNA became undetectable. C-type natriuretic peptide was one order of magnitude more potent than ANP in cGMP production in cultured aortic smooth muscle cells. The clearance receptor density and its mRNA level increased tremendously in these cultured cells. These results demonstrate that the marked phenotype-related alteration occurs in the expression of natriuretic peptide receptors in rat aortic smooth muscle cells.

ISSN:0009-7330    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

Adult rat ventricular myocytes undergo a well-documented sequence of phenotypic changes during adaptation to primary culture. However, we observed that coculture of myocytes with a specific subset of nonmyocyte cardiac cells could slow and even reverse the process of adaptation. These nonmyocyte cells were isolated and identified by immunohistochemical and ultrastructural criteria as being of epicardial mesothelial origin. When added to long-term primary cultures of adult ventricular myocytes, epicardial mesothelial cells appeared to induce myofibrillar arrays that were more organized than those seen in noncocultured myocytes; these changes that occurred were concurrent with the appearance of large amplitude contractions and multicellular synchronous beating that was facilitated by gap junctions between myocytes and epicardial mesothelial cells. The changes in morphology and function were accompanied by a marked increase in β-myosin heavy chain isoform transcription in cocultured myocytes, a return to the ratio of cardiac to skeletal α-actin expected in adult rat myocardium, and a much reduced expression of smooth muscle α-actin. These changes in myocyte phenotype and function appeared to require epicardial cell-myocyte contact, or close apposition, because media conditioned by epicardial mesothelial cells alone or in coculture had no effect. Thus, these rapid and reversible changes in myocyte ultrastructure, function, and gene expression may provide a useful in vitro model with which to study the mechanism responsible for regulating the plasticity of ventricular myocyte phenotype and the role of specific cell-cell interactions.

ISSN:0009-7330    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

It has been hypothesized, based on physiological evidence, that there is a greater proportion of β2-adrenergic receptors on the myocytes of the conduction system when compared with the working myocardium. The purpose of these studies was to examine β-adrenergic receptor subtype in the conduction system of the dog by using the technique of coverslip autoradiography. Scintillation studies of [125I]pindolol binding to ventricular sections demonstrated that binding was saturable (dissociation constant of 116 pM), had the correct order of potency for a 13-receptor, and was stereoselective. Both betaxolol (β1-selective) and ICI-118,551 (β2-selective) competition curves fit a two-site model in nonlinear curve-fitting analyses (78% β1-receptors). Autoradiographic studies determined that the myocytes of the sinoatrial node had approximately twice as many autoradiographic grains as the surrounding atrial myocytes. The myocytes of the atrioventricular bundle had a number of grains similar to the number in surrounding septal myocytes. Autoradiographic inhibition curves with betaxolol or ICI-118,551 demonstrated that both the sinoatrial node and the atrioventricular bundle had inhibition profiles similar to the surrounding myocytes (predominantly β1) but unlike the inhibition profiles of arterioles (predominantly β2). Calculations using the dissociation constants derived from the nonlinear curve-fitting analysis and the percent specific binding in the presence of 4×10−7M betaxolol or ICI-118,551 determined that the proportion of β1to β2-receptors was the same (70–80% β1) when comparing the sinoatrial node and the surrounding atrial myocytes. The atrioventricular bundle had a higher percentage of β1-receptors (95%) than the surrounding septal myocytes (79%) with betaxolol, but with ICI-118,551 the difference was not significant. Thus, by using techniques that can precisely quantify adrenergic receptors over myocytes of the conduction system, it was concluded that, whereas the myocytes of the sinoatrial node have approximately twice as many β-receptors as the surrounding atrial myocytes, the proportion of β1- to β2-receptors is the same.

ISSN:0009-7330    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

Intracellular free calcium concentration ([Ca2+]i) was measured in isolated ferret ventricular papillary muscles during and after long exposures to ischemia. All experiments were performed at 37°C, and the muscles were stimulated at 1 Hz. Ischemia was simulated by changing from superfusion with oxygenated Tyrode's solution to superfusion with water-saturated gas (95% N2-5% CO2), thus simultaneously stopping oxygenation and restricting the extracellular space. [Ca2+]iwas measured with aequorin, which was microinjected into superficial cells of the preparation. Exposure to ischemia caused a complex series of changes in [Ca2+]i. In the first few minutes the changes in [Ca2+]iwere variable; however, after approximately 5 minutes all preparations exhibited a progressive increase in amplitude and duration of the stimulated rise in [Ca2+]i(the calcium transient). The amplitude of the calcium transients peaked after approximately 18 minutes of ischemia, when they were 339% of the control value. After this peak, the calcium transients progressively failed to occur in response to stimulation and declined in amplitude; simultaneously, spontaneous oscillations of [Ca2+]iappeared and increased in size and frequency. The oscillations in turn then gradually became less frequent until a large, prolonged (5–10 minute) increase in [Ca2+]ioccurred, after which [Ca2+]ireturned to a low level. There were no further oscillations after this event, which was seen on average after 37 minutes of ischemia. A slowly progressive contracture often began to develop at about this time. A gradual rise in resting [Ca2+]ioccurred during the remainder of the exposure to ischemia. When muscles were reperfused after long exposures to ischemia, there was a very large and prolonged increase in [Ca2+]i, which was usually associated with a contracture and failure of recovery of developed tension. The large increase in [Ca2+]icould be reduced by the inclusion of 3 mM nickel chloride in the reperfusing solution. Comparison between reperfusion with O2gas versus reperfusion with anoxic Tyrode's solution indicated that reoxygenation was more beneficial to the muscle than resumption of bulk flow. These results reveal the complex spectrum of changes in [Ca2+]ithat occur during ischemia and on reperfusion. These changes in [Ca2+]iare likely to play an important role in the generation of ischemic arrhythmias and muscle damage.

ISSN:0009-7330    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

To study the mechanism of vasodilation induced by 6-(3-dimethylaminopropionyl) forskolin (NKH477), a water-soluble forskolin derivative, its effects on the acetylcholine (ACh)-induced contraction of muscle strips of porcine coronary artery were examined. [Ca2+]i, isometric force, and cellular concentrations of cAMP and inositol 1,4,5-trisphosphate were measured. NKH477 (0.1–1.0 μM), isoproterenol (0.01–0.1 μM), or forskolin (0.1–1.0 μM) increased cAMP and attenuated the contraction induced by 128 mM K+or 10 μM ACh in a concentration-dependent manner. These agents, at concentrations up to 0.3 μM, did not change the amount of cGMP. NKH477 (0.1 μM) attenuated the contraction induced by 128 mM K+without corresponding changes in the evoked [Ca2+]iresponses. ACh (10 μM) produced a large phasic increase followed by a small tonic increase in [Ca2+]iand produced a sustained contraction. The ACh-induced phasic increase in [Ca2+]i, but not the tonic increase, disappeared after application of 0.1 μM ionomycin. NKH477 (0.1 μM) attenuated both the increase in [Ca2+]iand the force induced by 10 μM ACh in muscle strips that were not treated with ionomycin and inhibited the ACh-induced contraction without corresponding changes in [Ca2+]iin ionomycin-treated muscle strips. These results suggest that NKH477 inhibits ACh-induced Ca2+mobilization through its action on ionomycin-sensitive storage sites. In ionomycin-treated and 128 mM K+-treated muscle strips, 0.1 μM NKH477 shifted the [Ca2+]i-force relation to the right in the presence or absence of 10 μM ACh. In β-escin-skinned smooth muscle strips, 0.1 μM NKH477 shifted the pCa-force relation to the right but had no effects on Ca2+-independent contraction. We conclude that in smooth muscle of porcine coronary artery, NKH477 inhibits ACh-induced contraction by both attenuating ACh-induced Ca2+mobilization and reducing the sensitivity of the contractile machinery to Ca2+, possibly by activating cAMP-dependent mechanisms.

ISSN:0009-7330    

出版商:OVID    

年代:1992

数据来源: OVID