![]() ![]() Calcium supplements: Do they interfere with blood pressure drugs?.Bump on the head: When is it a serious head injury?.Bone and joint problems associated with diabetes.Blood sugar levels can fluctuate for many reasons.Blood pressure tip: Know alcohol limits.Blood pressure readings: Why higher at home?.Blood pressure medications: Can they raise my triglycerides?.Blood pressure medication: Still necessary if I lose weight?.Blood pressure: Is it affected by cold weather?.Blood pressure: Does it have a daily pattern?.Blood pressure: Can it be higher in one arm?.Beta blockers: How do they affect exercise?.Beta blockers: Do they cause weight gain?.Artificial sweeteners: Any effect on blood sugar?.Anxiety: A cause of high blood pressure?.Angiotensin-converting enzyme (ACE) inhibitors.Alcohol: Does it affect blood pressure?.2017 ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA guideline for the prevention, detection, evaluation, and management of high blood pressure in adults: A report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines. In: Rutherford's Vascular Surgery and Endovascular Therapy. Atherosclerotic risk factors: Hypertension. Preparations used as nasal decongestants can cause a rebound effect (increased congestion) after a few days of use. If the coronary circulation is impaired, as in patients with coronary artery disease, the decrease in myocardial oxygen supply/demand ratio can precipitate angina. Because alpha 1-agonists produce systemic vasoconstriction, the work and oxygen requirements of the heart increase. Side Effects and Contraindications - α 1-agonistsĪlpha 1-agonists can cause headache, reflex bradycardia, excitability, and restlessness. α 2-adrenoceptor agonists (centrally-acting vasodilators Click here for details) Oxymetazoline, tetrahydrozoline, xylometazoline and some preparations of phenylephrine are used as nasal decongestants primarily because of their α 1 vasoconstrictor properties. ![]() Midodrine (oral form) is used in patients with autonomic insufficiency and symptomatic postural hypotension. form) is used as a pressor agent in treating hypotension and shock. Midodrine (prodrug converted to desglymidodrine) α 1-adrenoceptor agonists (systemic vasoconstrictors) These drugs include the naturally occurring catecholamines, dopamine, epinephrine and norepinephrine, as well as catecholamine analogs such as dobutamine. Besides the drugs listed below, there are sympathomimetic drugs that have α-agonist and β-adrenoceptor agonist properties. Specific Drugs and Therapeutic UsesĪlpha-agonists used therapeutically are relatively selective or non-selective for α 1 or α 2-adrenoceptors. Constriction of the resistance vessels (small arteries and arterioles) increases systemic vascular resistance, whereas constriction of venous capacitance vessels increases venous pressure. Therefore, an α 2-agonist inhibits norepinephrine release from sympathetic nerves.Īlpha-agonists constrict both arteries and veins however, the vasoconstrictor effect is more pronounced in the arterial resistance vessels. There are also α 2-adrenoceptors located on the sympathetic nerve terminals that inhibit the release of norepinephrine and therefore act as a feedback mechanism for modulating the release of norepinephrine. These receptors are linked to Gi-proteins, and binding of an α 2-agonist to these receptors decreases intracellular cAMP, which causes smooth muscle contraction. Depending on the tissue and type of vessel, there are also α 2-adrenoceptors found on the smooth muscle. The α 1-adrenoceptors are the predominant α-receptors on vascular smooth muscle. These receptors are linked to Gq-proteins that activate smooth muscle contraction through the IP 3 signal transduction pathway and Rho-kinase pathway. Vascular smooth muscle has two types of alpha-adrenoceptors - alpha 1 (α 1) and alpha 2 (α 2). Some α-agonists bind to prejunctional receptors on sympathetic nerves, which inhibits norepinephrine release both peripherally and centrally in the brain. Most alpha-adrenoceptor agonists (α-agonists) that are used clinically bind to α-receptors on vascular smooth muscle and induce smooth contraction and vasoconstriction, thus mimicking the effects of sympathetic adrenergic nerve activation to the blood vessels. ![]()
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