The response of pulmonary vascular endothelial cells to monocrotaline pyrrole: cell proliferation and DNA synthesis in vitro and in vivo

• Published in: Toxicology and applied pharmacology 1998-05, Vol.150 (1), p.37-48
• Main Authors: Lappin, P.B. (Michigan State University, East Lansing.), Ross, K.L, King, L.E, Fraker, P.J, Roth, R.A
• Format: Article
• Language: English
• Subjects: ALCALOIDE; ALCALOIDES; ALKALOIDS; Animals; Antimetabolites - therapeutic use; Biological and medical sciences; BLOOD VESSELS; BOVIN; Bromodeoxyuridine - therapeutic use; CATTLE; CELL CULTURE; CELL CYCLE; Cell Cycle - drug effects; CELL DIVISION; Cell Division - drug effects; CELL LINES; Cell Survival - drug effects; CULTIVO DE CELULAS; CULTURE DE CELLULE; CYTOTOXICITY; DIVISION CELLULAIRE; DIVISION CELULAR; DNA - biosynthesis; DNA REPLICATION; Endothelium, Vascular - cytology; Endothelium, Vascular - drug effects; Endothelium, Vascular - metabolism; EPITELIO; EPITHELIUM; Flow Cytometry; GANADO BOVINO; Immunohistochemistry; In Vitro Techniques; Intestinal Mucosa - cytology; Intestinal Mucosa - drug effects; LUNGS; Medical sciences; Monocrotaline - analogs & derivatives; Monocrotaline - pharmacology; PERMEABILIDAD; PERMEABILITE; PERMEABILITY; Plant poisons toxicology; POUMON; PULMONARY ARTERY; Pulmonary Artery - cytology; Pulmonary Artery - drug effects; Pulmonary Artery - metabolism; PULMONES; PYRROLIZIDINE ALKALOIDS; RAT; RATA; RATS; REPLICACION; REPLICATION; TISSUE CULTURE; TOXICIDAD; TOXICITE; TOXICITY; Toxicology; VAISSEAU SANGUIN; VASOS SANGUINEOS
• ISSN: 0041-008X; 1096-0333
• DOI: 10.1006/taap.1998.8398

Monocrotaline pyrrole (MCTP) causes pulmonary vascular endothelial cell (EC) injury followed by progressive pulmonary vascular leak in vivo and the inhibition of EC proliferation in vitro. It was hypothesized that MCTP inhibits cell proliferation in vitro by interfering with cell cycle progression in a cycle phase-specific manner. Furthermore, it was proposed that early alterations in MCTP-induced lung injury leading to hypertension were associated with a similar inhibition of EC proliferation. Subconfluent cultures of bovine pulmonary artery endothelial cells (BECs) were synchronized with aphidicolin (APH), a reversible G1-S phase inhibitor. Upon removal of APH, BECs were exposed to MCTP (5 micrograms/ml) or its vehicle for a 4-h interval corresponding to either the G1-S, S-G2, or G2 through mitosis (M) phases of the cell cycle. Fluorescence-activated cell sorting (FACS) was used to identify MCTP-induced changes in cell cycle progression in BECs, and the transit of S phase cells through the cycle was characterized through the incorporation of bromodeoxyuridine (BrdU). Synchronized BECs exposed to MCTP between mid-S-G2 or G2 through M were briefly delayed in G2-M at 12 h but underwent cell division by 24 h. By contrast, BECs treated with MCTP immediately after release from APH block became arrested in G2-M at 24 h and showed evidence of continued DNA synthesis and hypertetraploidy, but they did not divide. In vivo, MCTP (3.5 mg/kg i.v.) administration caused an increase in arterial EC BrdU incorporation between Days 3 and 7, but no increase in EC density. During this same interval, pulmonary vascular permeability increased and persisted. In summary, MCTP inhibits cell proliferation in a cell cycle phase-dependent manner in vitro. The results suggest that a similar mechanism could occur in vivo and may be associated with delayed EC repair, a process that could contribute to persistent pulmonary vascular leak.