Nerve cells, signal transduction

The smooth muscle cell does not respond in an all-or-none manner, but instead its contractile state is a variable compromise between diverse regulatory influences. While a vertebrate skeletal muscle fiber is at complete rest unless activated by a motor nerve, regulation of the contractile activity of a smooth muscle cell is more complex. First, the smooth muscle cell typically receives input from many different kinds of nerve fibers. The various cell membrane receptors in turn activate different intracellular signal-transduction pathways which may affect (a) membrane channels, and hence, electrical activity (b) calcium storage or release or (c) the proteins of the contractile machinery. While each have their own biochemically specific ways, the actual mechanisms are for the most part known only in outline. 

The structural design of nerve cells is a striking example of dendritic architecture, which acts as a signal transduction system. Neurons are known to send out a series of long specialized processes that will either receive electrical signals (dendrites) or transmit these electrical signals (axons) to their target cells (Fig. 5.40). 

Alkali metal transport in biochemistry is a vital process in maintenance of cell membrane potentials of use, for example, in nerve signal transduction and is at the core of some of the early work on artificial ionophores that mimic natural ion carriers such as valinomycin. Ionophore mediated ion transport is much slower than transport through cation and anion ion channel proteins, however. 

Yamada T, Endoh T, Suzuki T. 1999. Inhibition of calcium channels by neurocinin receptor and signal transduction in hamster submandibular ganglion cells. J Auton Nerv Syst 76 1-8. 

Plants not only evolved allelochemicals with broad activities (see Section 1.3.1) but also some that can interfere vdth a particular target [3,6,17-19,25]. Targets that are present in animals but not in plants are nerve cells, neuronal signal transduction, and the endocrinal hormone system. Compounds that interfere with these targets are usually not toxic for the plants producing them. Plants have had to develop special precautions (compartmentation resin ducts, trichomes, laticifers) in order to store the allelochemicals with broad activities that could also harm the producer. 

The neurotransmitter receptors and signal transduction machinery within the synapse respond to patterns of electrical activity and instigate biochemical changes in the nerve cell and in so doing modify the brain in response to behavioral... 

---