Tracheal vascular response to hypertonic and hypotonic solutions

Area of Science:

• Physiology
• Respiratory System Biology
• Vascular Biology

Background:

• The upper respiratory mucosa humidifies inhaled air, a process dependent on respiratory epithelium and blood vessels.
• Studying the in vivo relationship between airway surface and mucosal vasculature has been challenging.

Purpose of the Study:

• To investigate the impact of varying osmolarity on rat tracheal mucosal blood vessel diameter.
• To elucidate the regulatory mechanisms of mucosal blood flow in response to airway surface conditions.

Main Methods:

• Utilized a specialized chamber for direct in vivo visualization of rat tracheal microvasculature.
• Superfused the tracheal luminal surface with solutions of varying osmolarity (200, 290, 500 mosM) at 37°C.
• Measured changes in arteriole and venule diameters in response to hypo-, iso-, and hypertonic solutions.

Main Results:

• Mucosal vessels exhibited significant changes in diameter based on solution osmolarity.
• Arterioles (51 ± 5.6 μm) constricted by 10 ± 2.18 μm in hypotonic (200 mosM) and dilated by 11 ± 1.55 μm in hypertonic (500 mosM NaCl) solutions.
• Observed reversible constriction and dilation patterns in venules, with changes readily reversible upon return to isotonic conditions.

Conclusions:

• Tracheal epithelial exposure to altered osmolarity regulates mucosal blood vessel diameter.
• Changes in airway surface osmolarity serve as a key regulator for mucosal vascular tone, potentially influencing air humidification.
• Findings provide in vivo evidence for osmolarity-mediated control of upper airway microcirculation.