+ Resolve Article
+ Follow Us
Follow on FacebookFollow on Facebook
Follow on TwitterFollow on Twitter

+ Translate
+ Subscribe to Site Feed
GeoScience Most Shared ContentMost Shared Content

Metabolism of platelet-activating factor in the guinea-pig heart

, : Metabolism of platelet-activating factor in the guinea-pig heart. Journal of Molecular and Cellular Cardiology 24(10): 1101-1111

Platelet-activating factor (PAF; 1-alkyl-2-acetyl-glycero-phosphocholine) is a biologically active phospholipid which is synthesized by a variety of blood cells and organ systems. PAF exerts many effects on the cardiovascular system including hypotension, depression of myocardial contractility and coronary constriction. The present study has examined the capacity of the guinea-pig heart to regulate the levels of exogenous PAF in two different models: isolated perfused heart and isolated ventricular myocytes. In the first model, isolated hearts were perfused with labeled PAF (10(-10) M) in a recirculating manner at flow rates of 15 ml/min (normal flow perfusion; NFP) and 2 ml/min (low flow perfusion, LFP). Exogenously provided PAF appeared in the tissue in a time-dependent manner. The rate of extraction of PAF was higher during LFP than during NFP. PAF was metabolized by the heart to two major products, lyso-PAF and 1-alkyl-2-acyl-sn-glycero-3-phosphocholine (1-alkyl-2-acyl-GPC). Lyso-PAF was found primarily in the perfusion buffer while both lyso-PAF and 1-alkyl-2-acyl-GPC were detected in the tissue. No qualitative difference in the metabolic products derived from PAF catabolism was observed between hearts undergoing NFP and LFP. Acetyl hydrolase activity was detected in the perfusion fluid at both flow rates, probably accounting for the formation of lyso-PAF in the perfusate. However, perfusion fluid from LFP contained a higher acetyl hydrolase activity, per micrograms of protein as compared to fluid from NFP. Isolated ventricular myocytes incubated with labeled PAF (3 x 10(-9) M) also converted it to 1-alkyl-2-acyl-GPC. Kinetic experiments suggested that PAF was initially deacetylated to form lyso-PAF and that this intermediate was then rapidly reacylated with a fatty acyl moiety at the sn-2 position. HPLC analysis of the fatty acids inserted at the sn-2 position of 1-alkyl-2-acyl-GPC revealed that the myocytes reacylated lyso-PAF predominantly with arachidonic acid. These data indicate that the guinea-pig heart may regulate PAF levels by at least two mechanisms: (1) it may release acetyl hydrolase into the vascular compartment, particularly under low flow conditions; and (2) the ventricular myocyte has the capacity to take up PAF and catabolize it to inactive products.


PMID: 1479612

Other references

Harper C.L.J.; Jacobsen S.B., 1993: Isotopic constraints on global differentiation during the early Hadean. Eos, Transactions, American Geophysical Union 74(16, Suppl

Matousek J., 1973: The effect of bovine seminal rnase on cells of crocker tumor in mice. Experientia (Basel) 29(7): 858-859

Frim J.; Rule G.S.; Rance M.A.; Male R.S.; Raaphorst G.P.; Kruuv J., 1976: The effect of membrane lipid perturbers on cold 5 celsius and freeze thaw survival of mammalian cells. Cryobiology 13(6): 645-646

Weir, B.L.; Munk, D.; Wright, S.; Roberts, B., 1994: Responses to PGR IV of upland and pima cottons in the San Joaquin Valley of California. Field trials were conducted in 1992-93 in the San Joaquin Valley, California, to evaluate the effect of PGR IV [gibberellic acids + IBA] on upland (Gossypium hirsutum) and pima (G. barbadense) cottons grown in 30- or 38-inch rows. PGR IV was appli...

Schurig, V., 2010: Chiral Separations - In honour of Prof. Volker Schurig. Journal of Chromatography. A 1217(7): 925-1182

Kazakov, A.E.; Vassieva, O.; Gelfand, M.S.; Osterman, A.; Overbeek, R., 2003: Bioinformatics classification and functional analysis of PhoH homologs. PhoH protein is a putative ATPase belonging to the phosphate regulon in Escherichia coli. EC-PhoH homologs are present in different organisms, but it is not clear if they are functionally related, besides nothing is known about their regulation. T...

Loffler, W., 1953: Problems in endocarditis. Wiener Medizinische Wochenschrift 103(43): 797-802

Margetis, K.; Rajappa, P.; Cope, W.; Pisapia, D.; Souweidane, M.M., 2016: Endoscopic diagnosis of an MRI-occult, low-grade glioma with ependymal dissemination. A 21-year-old man presented with triventricular hydrocephalus due to a tectal mass. He underwent an endoscopic third ventriculostomy, and multiple nodules were identified at the floor of the third ventricle intraoperatively. Surgical pathology of...

Sanford, L.D.; Fuchino, S.H.; Tidikis, D.E.; Ross, R.J.; Morrison, A.R., 1996: Effects of microinjections of alpha-1 and alpha-2 adrenoceptor agonists into the amygdala on sleep-wake states. Society for Neuroscience Abstracts 22(1-3): 148

Yoo D.J., 1970: The effect on growth and yield in rice m flooding. Research Reports Of The Office Of Rural Development (crop) (suweon): 30