100.YOHIMBINE IS A
A.ALPHA 1 BLOCKER
B.ALPHA 2 BLOCKER
C.BETA 1 BLOCKER
D.NONE
ANS:ALPHA 2 BLOCKER
Yohimbine blocks the pre- and post-synaptic alpha-2 adrenoceptors. Blockade of post-synaptic alpha-2 adrenoceptors leads to minor corpora cavernosa smooth muscle relaxation. In fact the majority of adrenoceptors in the corpora cavernosa are alpha-1. Blockade of pre-synaptic alpha-2 adrenoceptors leads to increased release of neurotransmitters in the central nervous system and in the corpora cavernosa penis such as nitric oxide, noradrenaline, and dopamine. Whether nitric oxide released in the corpora cavernosa has a relaxing effect, noradrenaline has a much powerful constricting effect by stimulating the unblocked alpha-1 adrenoceptors. Concomitant use of an alpha-1 blocking agent will prevent constriction caused by the increased adrenergic stimulation.
A.ALPHA 1 BLOCKER
B.ALPHA 2 BLOCKER
C.BETA 1 BLOCKER
D.NONE
ANS:ALPHA 2 BLOCKER
Yohimbine blocks the pre- and post-synaptic alpha-2 adrenoceptors. Blockade of post-synaptic alpha-2 adrenoceptors leads to minor corpora cavernosa smooth muscle relaxation. In fact the majority of adrenoceptors in the corpora cavernosa are alpha-1. Blockade of pre-synaptic alpha-2 adrenoceptors leads to increased release of neurotransmitters in the central nervous system and in the corpora cavernosa penis such as nitric oxide, noradrenaline, and dopamine. Whether nitric oxide released in the corpora cavernosa has a relaxing effect, noradrenaline has a much powerful constricting effect by stimulating the unblocked alpha-1 adrenoceptors. Concomitant use of an alpha-1 blocking agent will prevent constriction caused by the increased adrenergic stimulation.
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