Lusitropy

As lusitropy influencing the ability of the heart muscle ( myocardium) is called for the rapid and complete relaxation. It forms the functional contrast to inotropic ( contractility ), but the mechanical pumping action of the heart as important. Under positive lusitropy is an increase in relaxivity, understood negative lusitropy the corresponding decrease. Adrenaline and noradrenaline have positive lusitropic properties. Although an increased calcium concentration in the myocytes (eg, cardiac glycosides ) increases inotropy, but at the same time has a negative lusitropic effect, there remains more calcium in the cytoplasm.

Positive lusitropy

Positive lusitropic effect (increased rate of relaxation of the heart muscle ) by the sympathetic nervous system: norepinephrine activated in Arbeitsmyokard on beta-adrenoceptors and a stimulating G protein adenylate cyclase, thereby the levels of cyclic adenosine monophosphate increases (cAMP ). This increased level of cAMP activates protein kinase A, an enzyme which is released from inhibition of the phosphorylation of the protein phospholamban, the sarcoplasmic Ca2 - ATPase ( SERCA ). Thereby, at a time more Ca2 is pumped back from the cytoplasm into the sarcoplasmic reticulum of the heart muscle cell, and this may relax faster.