We have observed rapid and extensive depletion of cellular energy stores by ⌬ 9 -tetrahydrocannabinol (THC) in the pulmonary transformed cell line A549. ATP levels declined dose dependently with an IC50 of 7.5 g/ml of THC after 24-h exposure. Cell death was observed only at concentrations Ͼ10 g/ml. Studies using JC-1, a fluorescent probe for mitochondrial membrane potential, revealed diminished mitochondrial function at THC concentrations as low as 0.5 g/ml. At concentrations of 2.5 or 10 g/ml of THC, a decrease in mitochondrial membrane potential was observed as early as 1 h after THC exposure. Mitochondrial function remained diminished for at least 30 h after THC exposure. Flow cytometry studies on cells exposed to particulate smoke extracts indicate that JC-1 red fluorescence was fivefold lower in cells exposed to marijuana smoke extract relative to cells exposed to tobacco smoke extract.Comparison with a variety of mitochondrial inhibitors demonstrates that THC produced effects similar to that of carbonyl cyanide p-trifluoromethoxyphenylhydrazone, suggesting uncoupling of electron transport. Loss of red JC-1 fluorescence by THC was suppressed by cyclosporin A, suggesting mediation by the mitochondrial permeability transition pore. This disruption of mitochondrial function was sustained for at least 24 h after removal of THC by extensive washing. These results suggest that exposure of the bronchopulmonary epithelium to THC may have important health and physiological consequences. adenosine 5Ј-triphosphate; JC-1; marijuana; flow cytometry; mitochondrial membrane potential RECREATIONAL AND MEDICINAL USE of marijuana remains prevalent despite numerous reports of adverse and toxic consequences (1). The epithelial lining of the lung acts as the primary site exposed to the inhaled components of marijuana smoke, including the high concentrations of cannabinoids associated with the particulate tar fraction. Histopathological alterations in the lung resulting from marijuana smoking include proximal airway inflammation, reserve and goblet cell hyperplasia, squamous cell metaplasia, loss of epithelial microvilli, and cellular atypia (13,35). These changes have been observed by bronchoscopic visualization and by microscopic inspection of human airway mucosal biopsy specimens. The mechanisms underlying these effects, however, are poorly understood and have not been investigated extensively.We previously reported that exposure to marijuana smoke in vitro results in significant oxidative stress and suppression of fas-induced apoptosis (42,43). We have also observed that agents that compromise cell energetics, including antioxidants, enhance the cytotoxic effects produced by ⌬ 9

OBJECTIVES Postoperative fluid overload is ubiquitous in neonates and infants following operative intervention for congenital heart defects; ineffective diuresis is associated with poor outcomes. Diuresis with furosemide is widely used, yet there is often resistance at higher doses. In theory, furosemide resistance may be overcome with chlorothiazide; however, its efficacy is unclear, especially in lower doses and in this population. We hypothesized the addition of lower-dose, intravenous chlorothiazide following surgery in patients on high-dose furosemide would induce meaningful diuresis with minimal side effects. METHODS This was a retrospective, cohort study. Postoperative infants younger than 6 months, receiving high-dose furosemide, and given lower-dose chlorothiazide (1–2 mg/kg every 6–12 hours) were identified. Diuretic doses, urine output, fluid balance, vasoactive-inotropic scores, total fluid intake, and electrolyte levels were recorded. RESULTS There were 73 patients included. The addition of lower-dose chlorothiazide was associated with a significant increase in urine output (3.8 ± 0.18 vs 5.6 ± 0.27 mL/kg/hr, p < 0.001), more negative fluid balance (16.1 ± 4.2 vs −25.0 ± 6.3 mL/kg/day, p < 0.001), and marginal changes in electrolytes. Multivariate analysis was performed, demonstrating that increased urine output and more negative fluid balance were independently associated with addition of chlorothiazide. Subgroup analysis of 21 patients without a change in furosemide dose demonstrated the addition of chlorothiazide significantly increased urine output (p = 0.03) and reduced fluid balance (p < 0.01), further validating the adjunct effects of chlorothiazide. CONCLUSION Lower-dose, intravenous chlorothiazide is an effective adjunct treatment in postoperative neonates and infants younger than 6 months following cardiothoracic surgery.

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