Similarities and differences in the autonomic control of airway and urinary bladder smooth muscle

The airways and the urinary bladder are both hollow organs serving very different functions, i.e. air flow and urine storage, respectively. While the autonomic nervous system seems to play only a minor if any role in the physiological regulation of airway tone during normal breathing, it is important in the physiological regulation of bladder smooth muscle contraction and relaxation. While both tissues share a greater expression of M2 than of M3 muscarinic receptors, smooth muscle contraction in both is largely mediated by the smaller M3 population apparently involving phospholipase C activation to only a minor if any extent. While smooth muscle in both tissues can be relaxed by β-adrenoceptor stimulation, this primarily involves β2-adrenoceptors in human airways and β3-adrenoceptors in human bladder. Despite activation of adenylyl cyclase by either subtype, cyclic adenosine monophosphate plays only a minor role in bladder relaxation by β-agonists; an important but not exclusive function is known in airway relaxation. While airway β2-adrenoceptors are sensitive to agonist-induced desensitization, β3-adrenoceptors are generally considered to exhibit much less if any sensitivity to desensitization. Gene polymorphisms exist in the genes of both β2- and β3-adrenoceptors. Despite being not fully conclusive, the available data suggest some role of β2-adrenoceptor polymorphisms in airway function and its treatment by receptor agonists, whereas the available data on β3-adrenoceptor polymorphisms and bladder function are too limited to allow robust interpretation. We conclude that the distinct functions of airways and urinary bladder are reflected in a differential regulation by the autonomic nervous system. Studying these differences may be informative for a better understanding of each tissue

An analysis of energy-drink toxicity in the National Poison Data System

Context. Small studies have associated energy drinks-beverages that typically contain high concentrations of caffeine and other stimulants-with serious adverse health events. Objective. To assess the incidence and outcomes of toxic exposures to caffeine-containing energy drinks, including caffeinated alcoholic energy drinks, and to evaluate the effect of regulatory actions and educational initiatives on the rates of energy drink exposures. Methods. We analyzed all unique cases of energy drink exposures reported to the US National Poison Data System (NPDS) between October 1, 2010 and September 30, 2011. We analyzed only exposures to caffeine-containing energy drinks consumed as a single product ingestion and categorized them as caffeine-containing non-alcoholic, alcoholic, or "unknown" for those with unknown formulations. Non-alcoholic energy drinks were further classified as those containing caffeine from a single source and those containing multiple stimulant additives, such as guarana or yerba mate. The data were analyzed for the demographics and outcomes of exposures (unknown data were not included in the denominator for percentages). The rates of change of energy drink-related calls to poison centers were analyzed before and after major regulatory events. Results. Of 2.3 million calls to the NPDS, 4854 (0.2%) were energy drink-related. The 3192 (65.8%) cases involving energy drinks with unknown additives were excluded. Of 1480 non-alcoholic energy drink cases, 50.7% were children < 6 years old; 76.7% were unintentional; and 60.8% were males. The incidence of moderate to major adverse effects of energy drink-related toxicity was 15.2% and 39.3% for non-alcoholic and alcoholic energy drinks, respectively. Major adverse effects consisted of three cases of seizure, two of non-ventricular dysrhythmia, one ventricular dysrhythmia, and one tachypnea. Of the 182 caffeinated alcoholic energy drink cases, 68.2% were < 20 years old; 76.7% were referred to a health care facility. Educational and legislative initiatives to enhance understanding of the health consequences of energy drink consumption were significantly associated with a decreased rate of energy drink-related cases (p = 0.036). Conclusions. About half the cases of energy drink-related toxicity involved unintentional exposures by children < 6 years old. Educational campaigns and legal restrictions on the sale of energy drinks were associated with decreasing calls to poison centers for energy drink toxicity and are encouraged