Systemic Hypertension and Antihypertensive Drugs PDF

Part 1 1: Systtemic hy ypertens sion and d antihy ypertens sive dru ugs █ B...

Part 1 1: Systtemic hy ypertens sion and d antihy ypertens sive dru ugs █ Bas sic inform mation ▌Vasc cular smo ooth musc cle contrraction an nd relaxation Vasoco n is initiated by ope onstriction ening of vooltage gateed L-type Ca2+ chan nnels in 2+ the meembrane off vascular smooth m muscle cellss. Increase ed intracel lular Ca triggers osphorylation of myo the pho osin light ch e which iniitiates conttraction. hain kinase Vasodiilation is in nitiated by y either:  Activation of guanylyl cyclase → ↑cGMP → dephosp phorylationn of myos sin light ain kinase → smooth ms cha m relaxatiion.  Ope + ening of K chann nels in thee vasculaar smooth muscle ccell memb brane → smoooth ms sttabilization (hyperpolarization) → relaxation. ▌The v vascular endothellium and local vas somotor control c Besidee the neu ural contrrol of blo ood vesssels through the ssympathettic and parasympathetic systems, the vascu helium pro ular endoth oduces vaarious compounds that he elp controlling the vas scular tone e: Nitric o oxide It is a diffusible gaas with very v short half-life. It causes VD by (NO; orr EDRF) increasing g intracellu ular cGMP P. It protec cts againsst atheroscclerosis, high blood d pressure e, heart failure and th hrombosis.. PGI2 It is synergistic to NO. It cause es VD via specific s reeceptors Endoth helin Is a 21-a amino-acid d peptide. By its action on ETA recepptors, it causes se evere VC a and vascula ar smooth muscle hyypertrophy y. 149  Angiotensin- Located on the endothelial cell membrane and converts circulating converting angiotensin-I (synthesized by the action of renin on enzyme (ACE) angiotensinogen) to angiotensin-II. By its action on AT1 receptors, Ang-II causes VC and stimulates aldosterone release. Other factors Histamine causes VD, bradykinin (synthesized from kininogen) causes VD, and serotonin (released by platelets) causes VC. █ Management of systemic hypertension Systemic hypertension is persistent elevation of BP above 140/90. Classification of hypertension: According to etiology: primary (= essential, 90%) or secondary. According to type: systolic, diastolic, or mixed. According to degree: see table. Classification of blood pressure levels of the British Hypertension Society Category Systolic BP (mmHg) Diastolic BP (mmHg) Normal blood pressure