alpha-receptors

alpha-receptors

adrenaline receptors (Table 1)
Table 1: Effects of stimulation of alpha, beta and dopamine receptors
ReceptorActionStimulating drug
Alpha-1 (α1); postsynapticVasoconstriction; positive inotropism; antidiuresisAdrenaline +
Noradrenaline +++
Alpha-2 (α2); presynapticVasodilatation; inhibition of noradrenaline releaseAdrenaline +
Noradrenaline +++
Dopamine +
Alpha-2 (α2); postsynapticConstriction of coronary arteries; promotion of salt and water excretionAdrenaline +
Noradrenaline +++
Dopamine +
Beta-1 (β1); postsynapticPositive inotropism; chronotropism; renin releaseAdrenaline ++
Noradrenaline ++
Isoprenaline ++
Dopamine +
Beta-2 (β2); presynapticNoradrenaline release accelerated; positive inotropism; chronotropismAdrenaline +
Isoprenaline +++
Beta-2 (β2); postsynapticVasodilatation; relaxation of bronchial smooth muscleAdrenaline +
Isoprenaline +++
Dopamine1; postsynapticVasodilatation; diuresisDopamine ++
Dopamine1; presynapticInhibits noradrenaline releaseDopamine +

Plus signs indicate degree of effect.

References in periodicals archive ?
Increased tone and frequency of contractions are believed to result from stimulation of beta-receptors, and reduced activity from stimulation of alpha-receptors.
Women who experience anxiety during labor and have high adrenaline levels that stimulate the alpha-receptors, might present with dysfunctional labor.
Nerves to the penis release the neurotransmitter noradrenaline (a catecholamine), causing stimulation of alpha-receptors on the surface of adjacent smooth muscle cells.
To complicate matters further, different types of alpha-receptors (alpha-1 and alpha-2-subtypes) are located not only on the smooth muscle cells, but also directly adjacent on the nerve-buds, from where catecholamines and other neurotransmitters are released.