Histopharmacology of arteries


Certain drugs called vasodilators cause the dilatation of arteries thereby reducing pressure by reducing peripheral resistance. They are used for coronary thrombosis, e.g. glyceryl trinitride. They act on smooth muscle through intracellular cyclic GMP which acts through calcium transport, leading to relaxation.

Calcium is needed for smooth muscle contraction in the arteries and hence calcium blockers help to block calcium entry in the arterial myocytes. They include  - amlodipine, isradipine, angine  verapamil, nifedipine and are used to treat hypertension,  angina pectoris, cardiac arrhythmias, and Raynaud's disease.

Angiotensin converting enzyme (ACE) inhibitors cause relaxation by blocking ACE which assist the conversion of angiotensin I to angiotensin II, a potent vasoconstrictor. ACE inhibitors are used to treat hypertension. They include captopril and losartan. Vasoconstrictors like norepinephrine (α1 receptor agonist) or angiotensin can be used in hypotension and cause vasoconstriction. Other vasoconstrictors which work through α1 receptors are imadazolines  such as xylometazoline, metatraminol, ephedrine and pseudoephedrine). These may work through myoneural junctions at postynaptic terminal of muscle cells of muscular arteries or directly affecting the muscle cells in tunica media from blood.



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Electronic School of Medicine
Creator: Oluwole Ogunranti


Nerve ending on a muscle fiber in artery/arteriole.Nerve impulse releases
transmitters which act on receptors on muscle fibers. Such receptors can
 be blocked by antagonist drugs.











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