The acute administration of ethanol mobilizes a considerable amount of Mg2+ from perfused rat livers and isolated hepatocytes in a dose-dependent fashion in the absence of release of cellular K+ or lactate dehydrogenase (LDH) in the extracellular medium. Mg2+extrusion becomes detectable within 2 min and reaches the maximum within 8 min after ethanol addition, declining toward the basal value thereafter irrespective of the persistence of alcohol in the perfusion system and the dose of ethanol administered. The effect is the result of a specific impairment of Mg2+transport and/or regulatory mechanisms. In fact, Mg2+ extrusion does not occur under conditions in which 1) ethanol is replaced by an equivalent dose of DMSO, 2) amiloride or imipramine are used as inhibitors of the Na+/Mg2+exchanger, 3) extracellular Na+ is replaced by an equimolar concentration of choline chloride, and 4) 4-methylpyrazole is used to specifically inhibit alcohol dehydrogenase and cytochrome P-4502E1. Finally, the observation that the cellular level of ATP is markedly reduced after acute ethanol administration would suggest that Mg2+ extrusion results from a decreased buffering capacity of cytosolic Mg-ATP complex.

Early Renaissance scientists were heavily influenced by psychological, philosophical, religious, sociological, and anthropological problems that perpetuated blind adherence to classically accepted doctrines. The unchallenged theories of and , limited practice of cadaver dissection, and scarcity of books 1 during this time are just a few examples of early obstacles to the advancement of scientific thought. Printmaking and book printing, however, were breakthroughs that enabled science to progress by leaps and bounds. It is difficult to separate the advancements of printmaking and book printing because they are complementary. We will focus on the art of printmaking, present a synopsis of early printing, and discuss the corresponding development of the neurological sciences. CONTEMPORARY SCIENTIFIC PARADIGMSPerhaps the most complete and influential knowledge of brain function before the Renaissance was that of Galen. 2 Although most of his knowledge was derived from work on animal cadavers, he applied this knowledge to humans. Galen delineated many of the senses, discussed the cranial nerves, and described the autonomic nervous system. He also described the distinction between the sensory and motor nerves, which he based on the belief that the sensory nerves were softer than the motor nerves. Galen proposed that because the cerebrum was softer than the cerebellum, the former housed the senses, and the latter controlled motor function. Contrary to Aristotle, Galen believed that the brain rather than the heart was the seat of intelligence and that "animal spirits," although derived from the heart, were passed to the ventricles in the brain by way of the circulation. 3(pp17-22)

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