Modifications of the Langendorff Method for Simultaneous Isolation of Atrial and Ventricular Myocytes from Adult Mice.

A single cardiomyocyte is a vital tool in the cellular and subcellular level studies of cardiac biology and diseases as a fundamental unit of contraction and electrical activity. Hence, isolating viable, high-quality cardiomyocytes from the heart is the initial and most crucial experimental step. Comparing the various protocols for isolating the cardiomyocytes of adult mice, the Langendorff retrograde perfusion is the most successful and reproducible method reported in the literature, especially for isolating ventricular myocytes. However, isolating quality atrial myocytes from the perfused heart remains challenging, and few successful isolation reports are available. Solving this complicated problem is extremely important because apart from ventricular disease, atrial disease accounts for a large part of heart diseases. Therefore, further investigations on the cellular level to reveal the mechanisms are warranted. In this paper, a protocol based on the Langendorff retrograde perfusion method is introduced and some modifications in the depth of aorta cannulation and the steps that may affect the digestion process to isolate atrial and ventricular myocytes were simultaneously made. Moreover, the isolated cardiomyocytes are confirmed to be amenable to patch clamp investigation.

[Effect of continuous cropping and soil treatment on rhizosphere fungal community of Panax quinquefolium].

OBJECTIVE: To analyze the effects of continuous cropping and soil treatment on rhizosphere fungal community of Panax quinquefolium, and the correlation between rhizosphere fungal community and growth of P. quinquefolium. METHOD: Field plot trail of continuous cultivated P. quinquefolium was conducted, meanwhile continuous cropping soil was treated by organic carbon fertilizer plus methylene dithiocyanate and Kingbo respectively. The rate of seedling survival, root disease index and root weight were investigated. Dilution plating was used to analyze the rhizosphere fungal community, multiple comparisons including H, M(a) and J were performed between rhizosphere fungal community and growth of P. quinquefolium. RESULT: As to P. quinquefolium planted in continuous soil, the rate of seedling survival, root weight decreased, root disease index increased remarkably (P<0.05). Meanwhile the fungal counts decreased 50% -63% , the diversity index (H') decreased 39%-43%, while the ratio of Penicillium and Aspergillus increased. There was a significant negative correlation between rhizosphere fungal diversity and P. quinquefolium root disease index (r = -0.970, P=0.006). Organic carbon fertilizer plus methylene dithiocyanate treatment could improve the rate of seedling survival and root weight, and could partly increase the rhizosphere fungal diversity. CONCLUSION: In continuous cropping soil of P. quinquefolium, the rhizosphere fungal counts and diversity index decreased, meanwhile the fungal community composition changed. Organic carbon fertilizer plus methylene dithiocyanate treatment could improve the growth of continuous cultivated P. quinquefolium.

[Effect of organic amendments on soil fungi community and continuous cropping Panax quinquefolium].

OBJECTIVE: To study the effect of different organic amendments treated replant soil and to find the relations between the soil fungi community and the growth of Panax quinquefolium L. seedling. METHODS: The soil was treated with bone meal and Perilla frutescens root meal, the rate of seedling emergence, incidence of rot root and root weight were investigated. The fungi community and the pathogen, Fusarium solani and Phytophthora cactorum population were counted by soil dilution plating technique. RESULTS: The organic amendments especially Perilla frutescens root meal treated soil could reduce the population of Fusarium solani and Phytophthora cactorum in soil, thus lessen the root disease of continuous cropping Panax quinquefolium and increase survival of weedling. CONCLUSION: Adding suitable organic amendments in soil can change the soil fungi community and be beneficial to solving the replant problem of Panax quinquefolium.