ABSTRACT
The neurotransmitter molecule norepinephrine (noradrenaline) is located within densecore vesicles in sympathetic nerve terminals located within the prostate. The arrival of nerve impulses at the nerve endings provokes norepinephrine release by a process of fusion of these vesicles with the cell membrane of the nerve endings. Norepinephrine then diffuses across the synaptic gap to activate either α1-adrenoceptors, situated on the membrane of prostatic smooth muscle cells, or α2-adrenoceptors, located on the nerve terminal itself (Figure 26). These α2-adrenoceptors are autoregulatory in function and their blockade, by non-specific α-adrenoceptor blockers such as phenoxybenzamine, results in raised circulatory catecholamine levels with a consequent induction of tachycardia and palpitations.
