Cigarette Smoke Extract Causes Non-Apoptotic Cell Death in Neonatal Vascular Smooth Muscle Cells

Abstract 1730 Poster Session II, Sunday, 5/2 (poster 24)

INTRODUCTION: More than 40% of neonates in the United States are exposed to second-hand cigarette smoke, a risk factor for sudden infant death syndrome (SIDS) and respiratory infections, during the phase of normal postnatal pulmonary vascular remodeling. Antenatal exposure to cigarette smoke has also been associated with SIDS and pulmonary hypertension. Cigarette smoke contains nitric oxide (NO), carbon monoxide (CO), nicotine (NT), hydrocarbons e.g. benzopyrene (BZP), volatile substances e.g. acrolein (AC) and acetaldehyde (ATL), free radicals,etc. AIM: Study effects of cigarette smoke on vascular smooth muscle cells (VSMC) in the developing vasculature. METHOD: Neonatal VSMC were isolated from pulmonary (PASMC; main and resistance PA), carotid (CSMC), and splenic arteries (SSMC) of 2 day old piglets. Cigarette smoke extract (CSE) was prepared by bubbling cigarette smoke through MEM with 10% FBS. The effect of CSE on proliferation (electronic cell counts), cell viability (trypan blue estimation), apoptosis (DNA fragment assay), and nitrates/nitites in media (enzymatic assay) were studied. Old CSE (aged 5 days), NT, BZP, AC, ATL and hemoglobin (Hb; scavenger of NO and CO) were used to evaluate active components of CSE. RESULTS: (Figure) CSE and old CSE markedly diminished cell counts and cell viability in a dose-dependent manner in PASMC, CSMC, and SSMC without an increase in apoptosis or of nitrates/nitrites (<5 microM) in the supernatant. NT and BZP did not affect cell counts significantly while AC and ATL decreased cell counts and viability in a dose-dependent manner. Hb incompletely attenuated the effect of CSE and also increased proliferation of controls. CONCLUSIONS: Cigarette smoke inhibits neonatal vascular smooth muscle cell proliferation and induces non-apoptotic cell death, which may not be directly due to NT or BZP, but due to AC, ATL, CO, NO, or other compounds in cigarette smoke. SPECULATION: Cigarette smoke may alter fetal and neonatal pulmonary or systemic vascular remodeling, and this may play a role in the pathogenesis of pulmonary hypertension or SIDS, respectively.

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