Term
| How does NO act to relax smooth muscle? |
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Definition
| activates guanylate cyclase, which produces cGMP (which is broken down by PDE). cGMP activates protein kinase that prevents release of Ca from ER, leading to muscle relaxation. |
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Term
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Definition
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Term
| Nitroglycerin mode of action, effect/use |
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Definition
| NO donor, for acute angina, also reduces bp (dose dependent), requires sulfhydryl-containing cysteine -> depletion of cysteine = nitrate tolerance. |
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Term
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Definition
| Treatment of angina and cyanide poisoning (by creating methemoglobin which sequesters cyanide as non-toxic cyanomethemoglobin. Methemoglobin converted back to hemoglobin by methylene blue). Also illegal inhalant that produces euphoria (poppers). |
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Term
| isosorbide mononitrate and dinitrate |
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Definition
| NO donor with longer t1/2's (5 hrs/1 hr) than nitroglycerin (minutes, need expensive patches) |
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Term
| nicorandil, effect, arrhythmias? side effects? |
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Definition
| NO donor (increases cGMP) and K-channel opener (hyperpolarizes cell), arterial and venous relaxation/dilation; doesn't cause arrhythmias because is selective of vascular potassium channels (no opening of cardiac or pancreatic channels); mouth ulcers |
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Term
| Ranolazine mode of action, effect |
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Definition
| indirectly reduces available Ca in cardiac muscle by altering the transcellular late Na current which affects sodium dependent calcium channels, relaxes heart muscle and reduces cardiac ischemia (lack of O2) |
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Term
| Trimetazidine mode of action, effect |
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Definition
| shifts cardiac metabolism from fatty acid beta oxidation toward glucose oxidation reducing O2 consuption, relaxes cardiac muscle/cardioprotective |
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Term
| Ivabradine mode of action, effect |
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Definition
| Inhibits sinus node pacemaking current (enhanced PNS effect), slows heart rate without side effects of beta-1 blockers (reduced contractility) and beta-2 blockage (prevention of bronchodilation) |
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Term
| DON'T use NO donors with these drugs |
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Definition
| PDE 5 inhibitors like sildenafil (also relax smooth muscle, take off nitrates for the day), alpha-1 blockers (block constriction of blood vessels and reduce bp like NO donors) |
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