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1. It can simultaneously relax the coronary arteries in the normal blood supply area and the ischemic area, antagonize spontaneous or ergonovine-induced coronary artery spasm, increase the delivery of myocardial oxygen to patients with coronary artery spasm, and relieve and prevent coronary artery spasm. 2. It can inhibit myocardial contraction, reduce myocardial metabolism, and reduce myocardial oxygen consumption. 3. It can relax peripheral resistance vessels, reduce peripheral resistance, and can reduce systolic and diastolic blood pressure, reducing cardiac afterload. 4. It can delay the sinus node function and atrioventricular conduction of isolated hearts; electrophysiological studies on whole animals and humans have not found that this product has the effect of delaying atrioventricular conduction, prolonging the recovery time of the sinus node, and slowing down the sinus node rate.

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1. Clonidine is an α-receptor agonist; 2. It stimulates the α2 receptors on the central postsynaptic membrane of the hypothalamus and medulla oblongata, reduces the outflow of central sympathetic nerve impulses, and inhibits peripheral sympathetic nerve activity; 3. It stimulates the α2 receptors on the presynaptic membrane of peripheral sympathetic nerves, reduces the release of norepinephrine from peripheral nerves, reduces peripheral vascular and renal vascular resistance, slows heart rate, and lowers blood pressure; 4. The supine cardiac output is moderately reduced (15%~20%) without changing peripheral vascular resistance; orthostatic symptoms are milder or less common when tilted at 45°, and postural hypotension rarely occurs; renal blood flow and glomerular filtration rate remain basically unchanged.

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