Chronotropic response

Voss, H.P., Shukrula, S., Wu, T.S., Donnell, D., and Bast, A., A functional beta-2 adrenoceptor-mediated chronotropic response in isolated guinea pig heart tissue selectivity of the potent beta-2 adrenoceptor agonist TA 2005, /. Pharmacol. Exp. Ther., 271, 386-389, 1994. 

Colucci WS, Ribeiro JP, Rocco MB, et al. Impaired chronotropic response to exercise in patients with congestive heart failure. Role of postsynaptic beta-adrenergic desensitization. Circulation 1989 80 314-23. 

Ford GA, James OF. Effect of autonomic blockade on cardiac beta-adrenergic chronotropic responsiveness in healthy young, healthy elderly and endurance-trained elderly subjects. Clin Sci (Lond) 1994 87(3) 297-302. 

The blue-green alga Anabaena sp. produces a chlorine-containing cyclic decapeptide, puwainaphycin C (180), which elicits a strong inotropic effect in isolated mouse atria (ED50 0.2 ppm) without a concommitant chronotropic response [141]. 

Right atrium Left atrium Adrenergic nerves Neurogenic chronotropic response Neurogenic inotropic response NA release (ES-evoked) inhibition inhibition inhibition Endou et al., 1994... 

Endothelin also has effects on isolated cardiac preparations, although these are less marked than on vascular tissues. The positive inotropic response varies considerably between species [18]. In the most sensitive preparation, rabbit papillary muscle, there is little difference between the potency of ET-1, ET-2 or ET-3 [18]. There is also little difference between the small positive chronotropic responses to ET-1 and ET-3 [19]. 

The relative role of P-AR subtypes in modulation of cardiac chronotropy was tested with the nonselective P-AR agonist isoproterenol administered to P-AR-KO mice. Wild-type mice show a robust 200 beats per min increase in heart rate associated with an approx 30 mmHg drop in mean blood pressure. In P,-AR-KO mice, the heart rate response is attenuated by approx 50% (28). This residual response is not mediated directly by cardiac P2-ARs but by P2-AR-mediated vasodilation. The hypotensive effect of activating vascular p2-ARs leads to a baroreflex-mediated withdrawal of vagal tone. The chronotropic response to isoproterenol in prAR-KO mice can be blocked by atropine, amuscarinic receptor antagonist (35). 

Pi aMHC, WT Cardiac hypertrophy (94,95) T Cardiac fibrosis (94,95) and apoptosis (95) Cardiac dysfunction (94,95) T Intrauterine mortality (75) 4 Inotropic and chronotropic response to ISO (75)... 

Wobus, A. M., Wallukat, G. Hescheler, ). Pluripotent mouse embryonic stem cells are able to differentiate into cardiomyocytes expressing chronotropic responses to adrenergic and cholinergic agents and Ca channel blockers. Differentiation 48, 173-182 (1991). 

Our findings indicate that in resistance vessels NO attenuates adrenergic responses by a postjunctional action, but not by decreasing NE release. In the heart NO does not modulate the chronotropic response to adrenergic nerve stimulation, but does enhance NE overflow in association with coronary vasodilation and ischemia/reperfusion. 

Mehta D, Lau C-P, ward DE, et al. Comparative evaluation of chronotropic responses of QT sensing and activity sensing rate responsive pacemakers. PACE 1988 11 1405-1412. 

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