Reflex coronary vasoconstriction caused by gallbladder distension in anesthetized pigs

Area of Science:

• Cardiovascular Physiology
• Autonomic Nervous System Regulation
• Gastrointestinal-Cardiac Reflexes

Background:

• Gallbladder distension reflexly increases heart rate and arterial pressure.
• The impact of gallbladder distension on coronary circulation was previously unknown.
• This study investigated reflex changes in left circumflex blood flow due to gallbladder distension.

Purpose of the Study:

• To determine if gallbladder distension causes reflex changes in left circumflex blood flow.
• To elucidate the neural pathways involved in this reflex.
• To identify the specific receptors mediating the coronary response.

Main Methods:

• Left circumflex blood flow was measured in anesthetized pigs using an electromagnetic flowmeter.
• Gallbladder distension was induced using a balloon catheter.
• Pharmacological agents (atropine, propranolol, phentolamine) and surgical interventions (vagotomy, splanchnic nerve section) were employed.

Main Results:

• Gallbladder distension consistently decreased left circumflex blood flow.
• The response was mediated by afferent vagal pathways and efferent sympathetic mechanisms.
• Alpha-adrenoceptor blockade (phentolamine) abolished the coronary vasoconstriction.

Conclusions:

• Innocuous gallbladder distension induces a reflex coronary vasoconstriction in pigs.
• The reflex involves afferent vagal pathways.
• Efferent sympathetic mechanisms acting on alpha-adrenoceptors are crucial for this coronary response.