A pressor response to vibration in conscious rats

Area of Science:

• Physiology
• Cardiovascular Research
• Neuroscience

Background:

• Vibration is a common environmental stimulus that can induce physiological stress.
• Understanding the cardiovascular adaptations to vibration is crucial for occupational health and safety.

Purpose of the Study:

• To investigate the cardiovascular response in conscious rats subjected to vibration.
• To elucidate the roles of the sympathetic nervous system and adrenal medulla in mediating these responses.

Main Methods:

• Conscious rats were exposed to cage vibration (to-and-fro movement for 30 sec).
• Cardiovascular parameters including cardiac output, mesenteric flow, hindquarter flow, and arterial pressure were monitored using implanted probes and catheters.
• Pharmacological interventions (adrenalectomy, beta-adrenoceptor blockade with propranolol, alpha-adrenoceptor blockade with phentolamine) were employed.

Main Results:

• Vibration increased arterial pressure, heart rate, cardiac output, and hindquarter flow, while decreasing superior mesenteric flow.
• Heart rate increase was dependent on beta-adrenoceptors but not adrenal hormones.
• Hindquarter flow increase involved both adrenal hormones and beta-adrenoceptors, with residual flow after alpha-adrenoceptor blockade.
• Mesenteric flow decrease was mediated by alpha-adrenoceptors and diminished by adrenalectomy.

Conclusions:

• Cardiovascular response to vibration involves sympathetic nerve excitation and adrenomedullary secretion.
• Skeletal muscle exhibits exercise hyperemia, and vasoconstriction occurs in the mesenteric circulation.
• The findings delineate a complex interplay of neural and hormonal pathways in response to vibration.