Mesenteric Lymph Drainage Improves Cardiac Papillary Contractility and Calcium Sensitivity in Rats with Hemorrhagic Shock

Abstract

Myocardial dysfunction is an important adverse factor of hemorrhagic shock that induces refractory hypotension, and post-hemorrhagic shock mesenteric lymph (PHSML) return is involved in this adverse effect. This study investigated whether mesenteric lymph drainage (MLD) improves PHSML return-induced cardiac contractile dysfunction via the restoration of cardiomyocyte calcium sensitivity. A hemorrhage shock model was established by using a controlled hemorrhage through the femoral artery that maintained a mean arterial pressure of 40 ± 2 mmHg for 3 h. MLD and mesenteric lymph duct ligation (MLDL) were performed from 1 to 3 h during hypotension. The papillarymuscles of the heart were collected for measurement of calmodulin expression and for determining contractile responses to either isoprenaline or calcium. The results showed that either MLD or MLDL reversed the hemorrhagic shock-induced downregulation of calmodulin expression, a marker protein of cardiomyocyte calcium sensitization, in papillary muscles. MLD also improved the decreased contractile response and ±df/dt of the papillary muscle strip to gradientisoprenaline or calcium caused by hemorrhagic shock. These findings indicate that increased cardiac contractibility may be associated with the restoration of calcium sensitivity produced by PHSML drainage.