Angiotensin receptors: their pharmacological aspects and side effects

defined G _q -mediated calcium and protein kinase C signaling pathways as well as

intracellular signaling cascade till to the nucleus. These different pathways are

responsible for the regulation of gene transcription and the expression of proteins

which control the growth responses and proliferation of cell in Angiotensin-

II target tissues. Some of the later consequences of AT ₁ receptor activation are

counteracted by the structurally dissimilar AT ₂ receptor, which antagonizes the

effects of AT ₁ -mediated growth responses in several cell types, in particular

endothelial cells, cardiomyocytes, and ovarian granulosa cells. This account of the

AT ₁ receptor will address its gene expression, ligand binding, activation and signal

transduction pathways, and physiological roles in the regulation of the activity and

growth of its major target cells in cardiovascular, neuronal, and endocrine tissues.

Angiotensin-II receptor blockers are the new class of drugs which classified

under antihypertensive agents drugs .ARBs mode of action is different from other

Angiotensin converting enzyme (ACE) inhibitors. ACE also works on Renin

Angiotensin System. Because of binding to the receptor site, ARBs produces the

complete inhibition of Angiotensin-II action. A lot of ARB drugs are available in

the market. which are approved by Food and DrugAdministration for the treatment

of hypertension, for the use either alone or in combination with other drugs (SPI,

2002; Olin, 2002). The different drugs available in the market are condensartan,

eprosartan, irbesartan, losartan, olmesartan, telmisartan and valsartan.

Those drugs which are used for the lowering blood pressure can cause some side

effects like dizziness, headache, cold flu and others. Kidney failure, liver failure

and some allergic reactions like swelling around the mouth and throat are also

shows by these drugs but rarely. (Rodgers and Patterson, 2001).

Different Angiotensin-II receptor blocker shows same mode of action but all of

them has different efficacy and pharmacokinetic profile with low side effects.ACE

inhibitors affect the bradykinin level of body but ARBs do not affect bradykinin

level but they are contraindicated in pregnancy.

Pharmacology of Angiotensin Receptor Blocker

Pharmacology of ARBs depends on the Rennin Angiotensin Systen (RAS). In

RAS renin converts the angiotensinogen to an inactive decapeptide Angiotensin-I

(Dzau et al. , 1993; Urata et al. , 1990; Linz et al. , 1995). Then After angiotensin-I

is converted to angiotensin-II by Angiotensin converting enzyme. Angiotensin-II

is the main end product of this cycle. Different type of pathogenesis reactions

like essential Hypertension, reno-vascular hypertension, congestive heart failure

and renal disease associated with albuminuria are produced by angiotensin-II.

Because of ACE inhibitors, when rennin angiotensin system blocks its shows few

side effects also like cough, and angioedema (Burnier and Brunner, 2000; Bumier,

2001; Rodgers and Patterson, 2001).

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