Repetitive progressive thermal preconditioning hinders thrombosis by reinforcing phosphatidylinositol 3-kinase/Akt-dependent heat-shock protein/endothelial nitric oxide synthase signaling.

Objective: We compared the effects of modified progressive thermal preconditioning (PTP) and whole-body thermal preconditioning (TP) on stress responses, oxidative stress biomarkers, and arterial thrombosis formation, and explored their possible actions through phosphatidylinositol 3-kinase (PI3K)/Akt-dependent heat-shock protein (Hsp)/endothelial nitric oxide synthase (eNOS) pathways.

Methods: We divided four groups of 249 male Wistar rats into nonimmersed controls, TP, and one (1-PTP) and three consecutive cycles (3-PTP) of PTP in a 42°C water bath. We evaluated the stress responses, including hemodynamics, total energy transfer, endoplasmic reticulum (ER) stress marker glucose-regulated protein (GRP78), and blood reactive oxygen species level during TP or PTP treatment. We compared 1-PTP, 3-PTP, or TP effects on oxidative stress, intercellular adhesion molecule 1 (ICAM-1), Hsp70, tissue plasminogen activator (t-PA) and plasminogen activator inhibitor type 1 (PAI-1) activity, and vascular phosphorylated Akt (p-Akt) and eNOS (p-eNOS) expressions in a model of topical ferric chloride (FeCl(3))-induced carotid artery thrombosis.

Results: PTP significantly (P < .05) induced less hemodynamic fluctuations, total energy transfer, ER, and oxidative stress than TP did. After 24 or 72 hours of treatment, 1-PTP, 3-PTP, and TP significantly (P < .05) elevated carotid arterial Hsp70, p-Akt, and p-eNOS expression, significantly (P < .05) depressed FeCl(3)-enhanced vascular 2',7'-dichlorodihydrofluorescein diacetate, chemokine (C-X3-C motif) ligand 1 (CX3CL1), 3-nitrotyrosine, 4-hydroxynonenal, and ICAM-1 stain, PAI-1, and t-PA activity, leukocyte infiltration and thrombus size, and significantly (P < .05) delayed thrombus formation compared with controls. 3-PTP and TP had a higher (P < .05) protection than 1-PTP. PI3K/Akt, Hsp70, or N(G)-nitro-l-arginine methyl ester hydrochloride (L-NAME) inhibitors significantly (P < .05) depressed 3-PTP and TP-induced vascular protection.

Conclusions: Repetitive PTP is better than single PTP to hinder thrombosis formation via reinforcing PI3K/Akt-dependent Hsp70/eNOS signaling.