Transduction Messengers

Excitation of smooth muscle via alpha-1 receptors (eg, in the utems, vascular smooth muscle) is accompanied by an increase in intraceUular-free calcium, possibly by stimulation of phosphoUpase C which accelerates the breakdown of polyphosphoinositides to form the second messengers inositol triphosphate (IP3) and diacylglycerol (DAG). IP3 releases intracellular calcium, and DAG, by activation of protein kinase C, may also contribute to signal transduction. In addition, it is also thought that alpha-1 adrenergic receptors may be coupled to another second messenger, a pertussis toxin-sensitive G-protein that mediates the translocation of extracellular calcium. 

Depletion of ATP in the cells prevents maintenance of the membrane potential, inhibits the functioning of ion pumps, and attenuates cellular signal transduction (e.g., formation of second messengers such as inositol phos phates or cyclic AMP). A marked ATP depletion ultimately impairs the activ-itv of the cell and leads to ceil death. 

Seuwen K, Ludwig MG, Wolf RM (2006) Receptors for protons or lipid messengers or both J Recept Signal Transduct Res 26 599-610... 

The intracellular processes which precede membrane activation appear to differ from those of MOE neurones, in that cyclic nucleotide gating may not occur. The transduction process which induces current flow in snake VN neurones, utilises as a putative second-messenger the modulator compound inositol triphosphate — Ins. (1,4,5) P3 = IP3 (Liu et al, 1999 Taniguichi et al, 2000). The proposed channel component associated with the microvillous membrane is one of the transient receptor potential family (TRPC-2 Heading Fig., pp. 94), the p-splice... 

As with signal transduction and second messenger systems, the mechanism of gene activation allows for amplification of the hormone s effect. 

Interference with signal transduction by reducing second-messenger synthesis through. 

---