Figure 19

Figure 19 Second-messenger systems following stimulation of &lpha-adrenoceptors on the membranes of smooth muscle cells within the corpora involve guanidine nucleotide binding protein (G protein) and phospholipase C (PLC). The signal is amplified by two pathways involving inositol phosphate (IP₃) and diacylglycerol (DAG), respectively. The result is an increase in the level of intracellular calcium and consequent smooth muscle contraction