The study aimed to evaluate the differential expression of HSF1 and GM-CSF mRNA in PBMCs and correlate it with myocardial injury in crossbred Jersey heifers during heat stress. The study also assessed the effect of heat stress on cardiac electrical activity, vascular health, liver function and kidney function. The experiment was conducted in two phases: for heat stressed animals; HS in June (THI ranged from 80.0 to 89.8) and for control group i.e. not exposed to heat stress in January (THI ranged between 70.1 and 71.4). Results of the study revealed that the relative abundance of HSF1 and GM-CSF mRNA increased significantly (P < 0.05) in HS. Serum cardiac biomarkers such as CK-MB, AST and CRP were significantly elevated (P < 0.05) in HS. cTnI was detected ‘positive’ in nineteen out of twenty four cases in HS. Correlation of HSF1 and GM-CSF expression with concentration of LDH, CKMB, CRP and AST in HS was negative but non-significant (P > 0.05). Significant (P < 0.05) ECG findings in HS were increased heart rate, decreased RR interval, decreased PR interval, decreased QRS amplitude and decreased amplitude of P wave. Marked reduction (P < 0.05) in serum cholesterol and triglyceride levels was observed in HS. ALP, AST, bilirubin and urea levels in serum were significantly elevated (P < 0.05) in HS. In conclusion, cardiac enzymes in serum were significantly elevated in HS indicating myocardial injury. HSF1 and GM-CSF mRNA expression alone was inadequate in conferring cytoprotection to cardiac cells in HS. Cardiac electrical activity, vascular status, liver and kidney function were significantly altered in HS.

该研究旨在评估 PBMC 中 HSF1 和 GM-CSF mRNA 的差异表达，并将其与热应激期间杂交泽西岛小母牛的心肌损伤相关联。该研究还评估了热应激对心脏电活动、血管健康、肝功能和肾功能的影响。实验分两个阶段进行：针对热应激动物；6 月份的 HS（THI 介于 80.0 至 89.8 之间）和对照组，即一月份未暴露于热应激（THI 介于 70.1 和 71.4 之间）。研究结果显示HSF1和GM-CSF mRNA的相对丰度 在HS中显着增加（P <0.05）。CK-MB、AST 和 CRP 等血清心脏生物标志物显着升高（P < 0.05) 在 HS 中。cTnI 在 HS 的 24 例中的 19 例中检测到“阳性”。HSF1和GM-CSF表达与HS中LDH、CKMB、CRP和AST浓度呈负相关但不显着（P  > 0.05）。 HS 的显着（P < 0.05）心电图结果是心率增加、RR 间期缩短、PR 间期缩短、QRS 波幅减小和 P 波幅度减小。 在 HS 中观察到血清胆固醇和甘油三酯水平显着降低（P < 0.05）。血清中ALP、AST、胆红素和尿素水平显着升高（P < 0.05) 在 HS 中。总之，血清中的心肌酶在 HS 中显着升高，表明心肌损伤。单独的 HSF1 和 GM-CSF mRNA 表达不足以为 HS 中的心脏细胞提供细胞保护。HS 患者的心脏电活动、血管状态、肝肾功能显着改变。