Experimental Subarachnoid Hemorrhage Drives Catecholamine-Dependent Cardiac and Peripheral Microvascular Dysfunction.

Area of Science:

• Cardiovascular Physiology
• Neurocritical Care
• Translational Medicine

Background:

• Subarachnoid hemorrhage (SAH) is a severe neurological event often accompanied by cardiac dysfunction and peripheral microcirculation abnormalities.
• These peripheral complications can worsen brain injury, highlighting the need to manage them for better patient outcomes.

Purpose of the Study:

• To investigate the impact of SAH on cardiac function and peripheral vascular reactivity.
• To identify the underlying molecular mechanisms, including adrenergic receptor and tumor necrosis factor (TNF) signaling.

Main Methods:

• Utilized a blood injection model to induce SAH in a preclinical setting.
• Assessed cardiac function and hemodynamics using echocardiography and blood pressure measurements.
• Evaluated vascular reactivity in cremaster muscle arteries ex vivo using pressure myography.

Main Results:

• SAH led to myocardial stunning, reduced cardiac output, and increased myogenic vasoconstriction in cremaster arteries, mediated by beta- and alpha-adrenergic signaling, respectively.
• Adrenergic receptor antagonists effectively prevented cardiac injury and normalized vascular function.
• TNF gene deletion abolished the SAH-induced augmentation of myogenic reactivity, suggesting a role for membrane-bound TNF as a mechanosensor.

Conclusions:

• Elevated catecholamines during SAH negatively affect cardiac and vascular function through specific adrenergic pathways.
• Targeting adrenergic receptors with antagonists offers a potential therapeutic strategy for SAH-related cardiovascular complications.
• Membrane-bound TNF plays a critical role in mediating alpha-adrenergic-induced vasoconstriction augmentation post-SAH.