Cardiac Troponin I Phosphorylation Underlies Myocardial Contractile Dysfunction Induced by Hypothermia-Rewarming.

Cardiac Troponin I Phosphorylation Underlies Myocardial Contractile Dysfunction Induced by Hypothermia-Rewarming. Am J Physiol Heart Circ Physiol. 2019 Aug 02;: Authors: Tveita T, Arteaga GM, Han YS, Sieck GC Abstract Rewarming the intact heart after a period of hypothermia is associated with reduced myocardial contractility, decreased Ca2+ sensitivity and increased cardiac troponin I (cTnI) phosphorylation. We hypothesized that hypothermia/rewarming (H/R) induces left ventricular (LV) contractile dysfunction due to phosphorylation of cTnI at Ser 23/24. To test this hypothesis, the response of wildtype mice (n=7) to H/R was compared to transgenic mice expressing slow skeletal TnI (TG-ssTnI; n=7) that lacks the Ser 23/24 phosphorylation sites. Hypothermia was induced by surface cooling and maintained at 23-25ºC for 3 h. Subsequently, the animals were rewarmed to 37ºC. Left ventricular systolic and diastolic function was assessed using a 1.4 F pressure-volume Millar catheter introduced via the right carotid artery. At baseline conditions, there were no significant differences in LV systolic function between wildtype and TG-ssTnI mice, whereas measures of diastolic function (isovolumic relaxation constant (τ) and end-diastolic pressure-volume relationship (EDPVR)) were significantly (p<0.05) reduced in TG-ssTnI animals. Immediately after rewarming, significant differences between groups were found in cardiac output (CO; wildtype 6...
Source: American Journal of Physiology. Heart and Circulatory Physiology - Category: Physiology Authors: Tags: Am J Physiol Heart Circ Physiol Source Type: research