The regional arterial resistance of the mesentry and kidney vessels is reduced by
i.D1 + D2 + α. + β1(not β2) → agonist.
ii.The D1 receptors in renal and mesentric blood vessel are the most sensitive: - I.V. infusion of low dose dopamine dilates these vessels by ↑cAMP →↑es GFR and Na+ excretion.
iii.Use: - in cardiogenic or septic shock and severe CHF to increase BP and urine outflow.
i.Relatively selective β1agonist
ii.Used as inotropic agent in pump failure accompanying M.I., cardiac surgery and short term
a. Isoprenaline: → β1+ β2–sympathomimetic