Phe—Met—Arg—Phe—NH2 (FMRFa)-Related Peptides Inhibit Na/Ca Exchange in Pancreatic B Cells
- 118 Downloads
Two processes located at the cell plasma membrane appear to mediate Ca2+ extrusion from cells: the Ca2+ ATP ase and the process of Na/Ca exchange [1,2]. In the heart, Na/Ca exchange appears to be the predominant mechanism for Ca2+ extrusion, being able to restore and control basal Ca2+ level on a beat-to-beat basis . Although the existence of a process of Na/Ca exchange in the pancreatic B cell has been postulated for many years, the process was only recently characterized and shown to regulate cytosolic free Ca2+ concentration within the physiological range. One major factor that has hindered rapid progresses in our knowledge of the process of Na/Ca exchange is the lack of specific inhibitors of the exchange. Recently, opioïd analogs (e.g. naloxone) were shown to inhibit Na/Ca exchange in cardiac sarcolemmal vesicles . Likewise, peptides related to Phe— Met—Arg—Phe—NH2 (FMRFa) with naloxone-like activity were observed to induce complete inhibition of Na/Ca exchange . In addition, it was suggested that endogenous analogs of FMRFa may exert some of their physiological modulatory role by inhibiting Na/Ca exchange . FMRFa is a molluscan peptide with potent effects on heart, as well as on other muscles and nerves of molluscs. FMRFa-related peptides have also been localized in several mammalian tissues and appear to exert various actions in eluding antagonism to opioïd analgesia [6,7]. The aim of the present study was to examine the effects of FMRFa-related peptides on Na/Ca exchange in rat pancreatic islet cells.
KeywordsRelated Peptide Cell Plasma Membrane Solid Phase Peptide Synthesis Basal Uptake Hydroxyamino Acid
Unable to display preview. Download preview PDF.
- 2.M.P. Blaustein, Sodium/Calcium exchange and the control of contractility in cardiac muscle and vascular smooth muscle. J. C ardiovasc. Pharmacol. 12 (suppl.5):S56 (1988).Google Scholar
- 3.D.M. Bers, Species differences and the role of Sodium-Calcium exchange in cardiac muscle relaxation, in: “Sodium-Calcium exchange: proceedings of the second international conference”, Blaustein, M.P., DiPolo, R., Reeves, J.P. Eds. Ann. NY Acad. Sci. 639: 375 (1991).Google Scholar