Flashcards in Pharmacology Deck (273)
B1-adrenoceptor couples to the g-protein....
The sympathetic nervous system releases noradrenaline as a __________ _____________ and adrenaline as a ___________ ___________
B1-adrenoceptors are activated in which locations? (2)
Activations of b1-adrecopteors NASA positive/negative chronotropic force
Chronotropic is an increase in
Increase in heart rate in presence of noradrenaline is due to what?
Increase in slope of phase 4 of action potential
Reduction in threshold for AP initiation due to enhanced Ica
Increase in contractility in the presence of noradrenaline is due to?
Increased in phase 2 of AP
Sensitisation of contractile proteins to calcium
The duration of systole is ______in the presence of noradrenaline
Decreased - this is a positive lusitropic reaction
Noradrenaline causes a ______ in the efficiency of the heart muscle
Decrease - heart starts to use oxygen less efficiently
Effect of noradrenaline on the Na-K-ATPase
Increases activity which is important for the normal balance of ions across the membrane
Parasympathetic system releases ___ to the cardiac muscle
In the heart, ACh acts on ____ muscarinic cholinoceptors largely in the ______ cells
The M2 receptor couples to the ____ g-protein
Coupling through Gi decreases the activity of ______ _______ thus reducing _______. The ________ potassium channel is opened causing a hyperpolarisation mediated by _________
Adenylate cyclase, cAMP.
GIRK, G-by subunits
Parasympathetic action of the cardiac muscle is.... (3)
Decreased chronotropic effect
Slight decrease in contractility
Decreased conduction in AV node
Why does the parasympathetic stimulation of the heart have little/no effect on ventricular contractility?
There is no parasympathetic stimulation on the ventricles
Parasympathetic stimulation of the heart may cause ....
Arrhythmias to occur in the atria
Vagal manoeuvres can can be used to...
Suppress atrial tachycardia
The funny current is mediated by channels that are activated by....(2)
hyperpolarisation and cAMP
other name for funny current channels
Blocking HCN channels causes what?
decrease of slope of pacemaker potential and reduces HR
Drug used to block HCN channels
Selectively blocks HCN Channels - slows HR in angina and reduces cardiac O2 consumption
cAMP is converted to 5'AMP by ...
PDE - phosphodiesterase
Inhibition of PDE has a positive/negative inotropic
Drug which inhibit PDE in acute heart failure
Catecholamines that act as b-adrenoceptor agonists (3)
dobutamine, adrenaline, noradrenaline
Actions of b-adrenoceptor agonists
increase rate, force and CO and O2 consumption