Inhibition of cytochrome P-450 attenuates hypoxemia of acute lung injury in dogs.

The intravenous administration of ethchlorvynol (ECV), in dogs, resulted in an acute lung injury (ALI) characterized by a 200 +/- 80% increase in venous admixture and a 142 +/- 30% increase in extravascular lung water (EVLW). Pretreatment with the cytochrome P-450 inhibitor 8-methoxypsoralen prevented the ECV-induced increase in venous admixture but not the increased EVLW. These findings parallel those reported for cyclooxygenase inhibition in ECV-induced ALI and suggest that an arachidonic acid (AA) metabolite of pulmonary cytochrome P-450 activity may mediate the increase in venous admixture of ALI. We demonstrate that canine pulmonary microsomes metabolize [1-(14)C]AA to a variety of products, including the cytochrome P-450 metabolites 5,6-, 8,9-, 11,12-, and 14,15-epoxyeicosatrienoic acid (EET). In prostaglandin F2 alpha-contracted, isolated pulmonary venous rings, 5,6-EET induced relaxation in a concentration-dependent manner. This action of 5,6-EET was prevented by indomethacin (10(-5) M). These results suggest that may serve as the cyclooxygenase-dependent endogenous pulmonary vasodilator responsible for the increase in venous admixture of ECV-induced ALI.

Ethchlorvynol overdose.

Ethchlorvynol remains a drug that frequently surfaces in clinical emergency practice despite safer and more effective pharmaceutical agents on the market. Effects such as poisoning, dependence, ocular damage, and overdose continue to receive attention in the literature. Awareness of complications and treatment in ethchlorvynol exposure requires attention to a drug remaining clinically available without an appropriate clinical indication.

Inhibition of endothelial cell retraction by ATP depletion.

To determine the relationship among endothelial cell (EC) retraction, cell adenosine triphosphate (ATP), and the status of cellular actin, ATP levels, F-actin content, and cytochemical redistribution in bovine pulmonary artery endothelial cells were assessed. EC monolayers 7 days after confluence were exposed to ethchlorvynol (ECV), histamine, or cytochalasin B (cyto B) for time intervals from 5-90 minutes. All 3 agents resulted in endothelial cell retraction without significant effect on cellular ATP content. Sixty-minute incubation of monolayers in glucose-free media containing antimycin A and 2-deoxyglucose depleted cellular ATP to less than 10% of control levels. ATP depleted monolayers failed to retract when incubated with ECV, histamine, or cyto B. ATP depletion resulted in loss of the prominent EC margins but only a rare gap between adjacent cells. When ATP levels were allowed to recover, the ability of EC monolayers to retract was restored. Actin filaments in control monolayers localized to a dense peripheral band of actin, a paranuclear complex, and bundles of microfilaments orientated parallel to the long axis of the cell. ECV induced complete loss of the dense peripheral band and other changes in the actin disposition. Monolayers exposed to histamine showed a retraction of the dense peripheral band of actin to a subcortical position. Cyto B caused loss of the dense peripheral band and the longitudinal microfilament bundles. Monolayers depleted of ATP lost their dense peripheral band and exhibited a disorganized, tangled web of microfilaments. Neither histamine nor ECV modified the actin distribution in ATP-depleted monolayers, whereas exposure to cyto B resulted in substantial change in actin with formation of a rim inside the cell membrane and considerable loss of actin filaments. ECV or histamine induced a small reduction in F-actin content while cyto B resulted in a 50% decline in 15 minutes. ATP depletion resulted in a 19% decrease in F-actin, with no further reduction on subsequent exposure to histamine or ECV. Cyto B treatment of ATP-depleted monolayers caused a drop in F-actin content equivalent to that observed in cells with normal ATP levels. These studies indicate that ATP is essential for changes in actin filament distribution and endothelial cell retraction produced by ECV, histamine or cyto B, and make it unlikely that any of these agents acts simply by depolymerization of actin filaments or modification of the dense peripheral band, although disruption of the dense peripheral band may facilitate retraction in the presence of adequate levels of cell ATP.

The effect of ethchlorvynol on cultured endothelial cells. A model for the study of the mechanism of increased vascular permeability.

Ethchlorvynol (ECV), an agent which produces reversible pulmonary edema, was studied for its effects on cultured bovine pulmonary artery endothelial cell (BPAE) and human umbilical vein endothelial cell (HUVE) monolayers. Endothelial cell monolayers 6 days post-confluent were treated with 1 mg/ml ECV for time intervals of from 5 minutes to 15 hours. ECV treatment caused a mild endothelial cell retraction evident at 10 minutes which increased in severity with increasing duration of exposure to ECV. Retraction of endothelial cells resulted in the formation of irregularly delineated gaps between cells, which remained attached to one another by slender filamentous processes. Despite the severity of the endothelial cell lesion, no cell lysis or cell detachment from the substratum occurred. Furthermore, removal of ECV from cell cultures resulted in the reversal of the endothelial cell lesion. Cytochemical distribution of actin microfilaments in control monolayers localized to a dense peripheral band of actin filaments and to a set of interconnected central microfilaments oriented in general parallel to the long axis of the cell. Endothelial cells treated with ECV for as little as 10 minutes showed a loss of F-actin from the dense peripheral band of microfilaments progressing until the dense peripheral band was entirely lost after 4 hours' exposure to ECV. By 4 hours central microfilaments had reorganized into a prominent series of microfilament bundles aligned parallel to each other and to the long axis of the cell. For investigation of a possible loss of attachment sites of actin filaments as the basis for the lesion, the localization of vinculin was examined in control and ECV-treated BPAE monolayers. After 2 hours' exposure to ECV, vinculin localization within monolayers was affected little, if at all. No effects of ECV on intermediate filaments were observed either. It is proposed that the dense peripheral band of actin bundles is important in maintaining well-spread endothelial cells in monolayers and that ECV acts to destroy the integrity of this structure. It is further proposed that a reaction of endothelial cells to ECV in vivo analogous to that seen in tissue culture accounts for the production of pulmonary edema by creating gaps between cells.

Lipid solubility is correlated with hypnotic and hypothermic responses of long-sleep (LS) and short-sleep (SS) mice to various depressant drugs.

The long-sleep (LS) and short-sleep (SS) lines of mice have been selected for a difference in duration of ethanol-induced sleep time. In our previous study, recent generations of the two lines were found to exhibit differential hypnotic and hypothermic responses to pentobarbital which appear to be explained by differences in elimination. Casual observation that the LS mice were fatter than the SS suggested that this discrepancy may influence the responses of these animals to sedative-hypnotic drugs which differ in lipid solubility. The present study was designed to determine whether the LS and SS mice differ in hypnotic and hypothermic responses to two barbiturates which differ in lipid solubility; to the highly lipid soluble tertiary alcohol, ethchlorvynol; and to the water soluble depressant, methyprylon. Mice of the SS line were more responsive to the lipid soluble depressants than were LS mice, and increasing the lipid solubility of the barbiturates resulted in a greater difference between the lines. LS mice were more responsive to the water soluble depressant, apparently due to differential central nervous system sensitivity rather than to differences in elimination. The whole-body lipid content of the LS mice is double that of the SS mice. The influence of body lipid content on drug disposition may accentuate the elimination differences that result in the lesser responsivity of LS mice to barbiturates and possibly ethchlorvynol. This study indicates that sedative-hypnotic drugs of varying lipid solubilities may not share common mechanisms of action.

Increases in lung lymph and albumin clearance with ethchlorvynol.

We studied anesthetized dogs with right lymph duct (RLD) preparations and measured lymph flow, albumin concentrations in lymph (L) and plasma (P), pulmonary artery pressure (PAP), and pulmonary capillary wedge pressure (PCWP). Intravenous (iv) injection of ethchlorvynol (15-25 mg/kg) was followed by significant (p less than 0.02) increases in right lymph duct flow from 0.9 +/- 0.3 to 5.4 +/- 1.6 ml/h with stable PAP, PCWP, and L/P albumin (0.8 +/- 0.05 and 0.9 +/- 0.1). Similar results in RLD flow were obtained in dogs given 1) diphenhydramine, 3 mg/kg iv loading dose and 1.5 mg.kg-1 .h -1 infusion; 2) indomethacin, 4 gm/kg iv loading dose and 4 mg.kg-1h-1 infusion; 3) methylprednisolone, 30 mg/kg iv; 4) cyclophosphamide (40 mg/kg iv) to induce leukopenia (900 WBC/mm3) prior to ethchlorvynol injection. Cardiac lymph flow increased also and cardiac L/P albumin remained stable. Total hemolytic complement remained normal. We conclude that lung vascular permeability is increased following ethchlorvynol injection. Ethchlorvynol may have a direct effect on lung vascular permeability since, unlike other experimental models, complement activation, leukocytes, prostaglandins, and histamine play insignificant roles. A "final common pathway" may not exist for all forms of increased permeability pulmonary edema.

Polygraphic evaluation of ethchlorvynol (14 days).

Ethchlorvynol 500 mg was administered to four young insomniacs for 14 days as part of a standard 22-day sleep laboratory protocol. Subjects slept more while receiving drug, but these benefits were not statistically significant. Ethchlorvynol impaired mood during both drug and withdrawal periods as compared to baseline, and serious side effects were reported. Stage REM and stage 1 were suppressed by ethchlorvynol, and stage 1 (but not stage REM) showed withdrawal rebound.

The effects of ethchlorvynol on pulmonary alveolar membrane permeability.

Intravenous injection of ethchlorvynol (Placidyl) causes noncardiogenic pulmonary edema in humans and laboratory animals. We studied the effects of intravenous ethchlorvynol (15 to 25 mg per kg of body weight) on pulmonary alveolar membrane permeability to various endogenous and exogenous solutes in the in vivo saline-filled dog lung model. Baseline and postethchlorvynol times in minutes for 50 per cent equilibration between the blood and saline-filled alveoli were, respectively, for urea, 37.3 +/- 12.4 and 12 +/- 6.3; for albumin 8,160 +/- 4,400 and 267 +/- 93; for dextrans of molecular weight 10,400 daltons, 1,150 +/- 80 and 185 +/- 160; for dextrans of molecular weight 250,000 daltons, 24,000 +/- 800 and 1,120 +/- 900; for dextrans of molecular weight 500,000 daltons, 24,500 +/- 150 and 1,020 +/- 590. All of these pairs of values were significantly different (P less than 0.01). In addition, lung liquid histamine (but not blood histamine) concentrations increased significantly (P less than 0.001) after ethchlorvynol injection. Intravenous ethchlorvynol causes marked increases in alveolar membrane permeability.

Ethchlorvynol (Placidyl)-induced pulmonary edema.

Two patients experienced severe nonhemodynamic pulmonary edema following the intravenous injection of 25 and 40 mg/kg of body weight of ethchlorvynol (Placidyl). The pulmonary edema cleared rapidly. Injection of Placidyl (12 to 80 mg/kg of body weight) intravenously into dogs caused acute, severe, nonhemodynamic pulmonary edema (as evidenced by markedly elevated lung weights and microscopic evidence of intra-alveolar edema), hypotension with a relative bradycardia, and a decreased cardiac output. Injection of polyethylene glycol, the vehicle in which ethchlorvynol is diluted, did not reproduce the syndrome.