Airway hyperresponsiveness in asthma. Is it unique?

Bronchial hyperreactivity in patients who inhale heroin mixed with cocaine vaporized on aluminum foil

BACKGROUND

In our area, inhaling heroin mixed with cocaine vaporized on aluminum foil, known as rebujo, is becoming more and more common.

AIM

To define the prevalence and the characteristics of bronchial disease (wheezing, bronchial hyperreactivity [BHR], and asthma) present in subjects inhaling heroin mixed with cocaine vaporized on aluminum foil.

MATERIALS AND METHODS

Ninety-one subjects who inhaled the drug mixture were included in the study: 62 subjects were from a drug rehabilitation center (INH-I group), and 29 subjects were among patients admitted to our hospital for a variety of reasons (INH-II group). A questionnaire was completed in both groups, as well as IgE determination and lung function tests (spirometry and methacholine challenge). The control group consisted of 122 individuals who did not inhale the drug mixture, and were chosen randomly from the general population (NO-INH group). All subjects were tobacco smokers.

RESULTS

In the INH-I group, there was a 41.9% prevalence of wheezing over the past 12 months, a 44.4% prevalence of BHR, and a 22.02% prevalence of asthma, defined as wheezing plus BHR. In the NO-INH group, these values were 32.78% (p = 0.22), 15.57% (p < 0.0001), and 8.19% (p < 0.01), respectively. Of the subjects who inhaled the drug mixture and denied having symptoms prior to the use of the drug mixture, 31.4% had wheezing develop after commencing use of the drug, following a mean latency of 4.09 months. Wheezing remitted in only 7.6% after discontinuation of the drug.

CONCLUSIONS

(1) There is a real increase in BHR in subjects who inhale heroin mixed with cocaine vaporized on aluminum foil; and (2) this BHR is associated with wheezing that develops after a variable period of latency, once drug inhalation begins, and persists despite discontinuation of the drug.

Effects of various reactive oxygen species on the guinea pig trachea and its epithelium

Reactive oxygen species (ROS) are key factors playing important roles in tissue damage of airways under different pathological conditions. Effects of ROS (superoxide anion, H2O2 and hydroxyl radical) were recorded on isometric tension of intact and epithelium denuded, not precontracted guinea pig trachea. Superoxide anion was produced by xanthine/xanthine oxidase and hydroxyl radical either by FeSO4/H2O2 or FeSO4/ascorbic acid. In intact preparations, the muscle tension was unaffected by superoxide anion, while H2O2 and hydroxyl radical produced a biphasic response, contraction followed by relaxation. Both the amplitude and duration of contractions evoked by H2O2 were larger than those caused by hydroxyl radical producing systems. On denuded tracheal strips, superoxide anion elicited also a biphasic response, and the H2O2 and hydroxyl radical produced contractions were of higher amplitude and of longer duration than in intact tissues. Indomethacin pretreatment enhanced or slightly reduced the amplitude of contractions evoked by both H2O2 and hydroxyl radical on the intact and denuded preparations, respectively. Moreover, the duration of contractions of the trachea induced by oxidative systems was prolonged. Indomethacin did not affect the action of superoxide anion on the intact tissues and reduced the amplitude of the biphasic response on denuded ones. Nordihydroguaiaretic acid pretreatment did not alter the responses elicited by ROS in intact preparations and reduced their action on the denuded ones. Our results suggest that a) various ROS contract tracheal smooth muscle with simultaneous release of epithelium derived relaxing factors, b) epithelium possesses superoxide anion scavenging capacity which is high enough to protect smooth muscle from its actions, and c) cyclooxygenase products participate in relaxation and lipoxygenase products in contraction caused by ROS in the guinea pig trachea.