Pramanicin, an antifungal agent, raises cytosolic Ca2+ and causes cell death in vascular endothelial cells.

Abstract

The effects of a newly discovered antifungal agent, pramanicin, on cytosolic Ca(2+) and cell viability of cultured bovine pulmonary artery endothelial cells and on endothelium-dependent relaxation of dog carotid arterial rings were investigated by digital dynamic fluorescence ratio imaging and morphological and contractility studies, respectively. Pramanicin 100 microM, previously shown to cause maximal endothelium-dependent and NO-mediated vascular relaxation, induced a small transient elevation of cytosolic Ca(2+) concentration in Ca(2+)-free medium; subsequent introduction of 1 mM Ca(2+) caused a steady, nonsaturating increase of Ca(2+), which could be brought down to the basal level by the addition of EGTA. At the single cell level, the elevation of cytosolic Ca(2+) initiates from the cell periphery and progresses toward the central region. When added to the plateau phase of phenylephrine-induced contraction, pramanicin induced a slow endothelium-dependent relaxation, which could be reversed with the NO synthase inhibitor, L-NOARG. When preincubated with vascular tissue, pramanicin resulted in an irreversible loss of endothelial function characterized by the lack of carbachol-induced relaxation. Pramanicin caused cell injury characterized by plasmalemmal bleb formation, leading to cell death characterized by Trypan blue staining of the nuclei in cultured vascular endothelial cells in a concentration- and time-dependent manner. Such pramanicin-induced cell death was not associated with Ca(2+)-mediated or NO-mediated mechanisms. The time course of Ca(2+) elevation corresponds with that of pramanicin-induced relaxation of precontracted arterial rings, whereas the time course of endothelial cell death corresponds to that of pramanicin-induced loss of endothelial function as assessed by carbachol-induced relaxation. The pramanicin analogue, PMC-A, a by-product of the biosynthesis of pramanicin, in which the epoxy group is replaced by a CC bond, caused little endothelial-dependent relaxation, but it was able to cause endothelial cell dysfunction, albeit to a lesser extent compared to pramanicin, suggesting a role of the epoxy group in pramanicin for its vasorelaxant effect.

• Authors: Chiu-Yin Kwan, Paul H M Harrison, Tony K Kwan
• Journal: Vascular pharmacology (Vascul Pharmacol) Vol. 40 Issue 1 Pg. 35-42 (Jan 2003) ISSN: 1537-1891 [Print] United States
• PMID: 12646408 (Publication Type: Journal Article)

Chemical References

• Antifungal Agents
• Epoxy Compounds
• Lactams
• pramanicin
• Calcium

Topics

• Animals
• Antifungal Agents (pharmacology)
• Calcium (metabolism)
• Cattle
• Cell Death (drug effects, physiology)
• Cells, Cultured
• Cytosol (drug effects, metabolism)
• Dogs
• Endothelium, Vascular (cytology, drug effects, metabolism)
• Epoxy Compounds (pharmacology)
• Female
• Lactams (pharmacology)
• Male