BMS 450 Lecture Notes - Mydriasis, Ipratropium Bromide, Vascular Resistance
Document Summary
Primary result of 1 stimulation is positive cardiac ionotropic and chronotropic effects. Antagonism: block endogenous ne and epi resulting in decreased heart rate and cardiac contractility. Magnitude dependent on sympathetic tone (consider exercise and stress) Excessive sympathetic stimulation is proarrythmogenic, cardiac arrhythmias. Antagonism: block endogenous epi (not ne!) resulting in increased bronchoconstriction, especially in patients with bronchospastic disease. Increased bronchoconstriction is not generally a desirable effect, major limitation of non-selective antagonists. Prototypical antagonist with equal affinity for 1 and 2 receptors. Selectivity is relative, block 2 receptors at higher doses. Advantage: safer to use in patients with bronchospastic disease. Bp = co x pr, blood pressure. Excessive sympathetic stimulation is pro-arrythmogenic, cardiac arrhythmias. Useful in congestive heart failure ( hr, oxygen demand, etc. ) Beta blockers used to be contraindicated in heart failure. Decrease heart rate, reduce cardiac oxygen demand, decrease blood pressure. Bradycardia (decreased sa nodal automaticity), decreased conduction (e. g. av node), decreased cardiac contractility.
