Differences in pharmacological properties and transduction mechanisms has led to issues concerning the classification and nomenclature of adenosine receptors (P1) and purinoceptors (P2). Proof that adenosine triphosphate operates through two distinct transduction mechanisms and developments in purinoceptor cloning stress the need to classify purinoceptors into G protein-coupled receptors and intrinsic ion channels. Revision of the nomenclature of the receptors, however, remains difficult since classification by pharmacologists are based on the receptor's structure.
Angela Sirigu et al. established that mentally rehearsed movements are duplicated in actual execution and that imagined movements are governed by the same physical laws and limitations as actual ones. Effects of brain lesions on movement imaging depend on location. Lesions affecting the frontal-striatal circuit, including the motor cortex and basal ganglia, do not seem to affect the imaging of movements, while those in the parietal cortex do. This suggests that evaluation of motor movement occurs in the latter.
Ion channels render nerve and muscle excitable. A typical channel protein can mediate the passive transfer of millions of ions per second across the membrane. Thus, channels catalyse the transmembrane flux of ions, fulfilling criteria traditionally associated with enzymes. Is this a semantic coincidence, or do channels and enzymes in fact rely upon similar structural principles? A general answer remains elusive given the paucity of crystallographic data on channels. Nevertheless, emerging evidence points to fundamental similarities between the pores of channels and the active sites of enzymes of resolved structure. Shared features include narrow clefts lined by protein loops, and specific binding of transition intermediates during catalysis. The often cited analogies between channels and enzymes might therefore reflect basic design homologies.
Pharmacology should be defined within its social and intellectual context. A survey of experts on the ideal definition of pharmacology reveals that most of them believe that pharmacology's main purpose is to hopefully obtain direct or indirect benefits for human beings and other selected species. Like other fields of study, pharmacology is fraught with ethical concerns particularly on respect for life in both tissues and whole organisms.
There is increasing evidence that nitric oxide (NO), a free radical that can act both as a signaling molecule and a neurotoxin, is involved in the mechanisms of cerebral ischemia. Although early investigations yielded conflicting results, the introduction of more-selective pharmacological tools and the use of molecular approaches for deletion of genes encoding for NO synthase have provided a better understanding of the role of NO in the mechanisms of ischemic brain damage. The evidence reviewed in this article suggests that NO is protective or destructive depending on the stage of evolution of the ischemic process and on the cellular source of NO. Defining the role of NO in cerebral ischemia provides the rationale for new neuroprotective strategies based on modulation of NO production in the post-ischemic brain.