Vasopressin induced rhythmic activity in rat basilar artery

Area of Science:

• Vascular Physiology
• Cardiovascular Research
• Neuroendocrinology

Background:

• Vasopressin plays a role in regulating blood pressure and vascular tone.
• Spontaneously hypertensive rats (SHR) exhibit altered vascular reactivity compared to normotensive controls.
• Basilar artery function is critical for cerebral blood flow regulation.

Purpose of the Study:

• To investigate the differential effects of vasopressin on isolated rat basilar arteries.
• To compare the vascular responses between normotensive Wistar-Kyoto (WKY) rats and stroke-prone spontaneously hypertensive (SP-SHR) rats.
• To explore the role of membrane potential and ion transport in vasopressin-induced contractions.

Main Methods:

• Isolated basilar artery segments from WKY and SP-SHR rats were used.
• Vasopressin was applied at varying concentrations (0.01-0.3 IU/ml).
• Membrane potential and tension were measured; experiments included K+-free and high K+ solutions.

Main Results:

• Vasopressin induced rhythmic contractions in WKY basilar arteries, but not in SP-SHR.
• Depolarization induced by vasopressin was similar in both rat strains.
• Rhythmic contractions were enhanced in K+-free solution and abolished in high K+ solution.

Conclusions:

• Vasopressin-induced rhythmic contractions in WKY basilar arteries are likely modulated by electrogenic Na+-K+ active transport.
• Reduced activity of the Na+-K+ pump may contribute to these rhythmic contractions in WKY rats compared to SP-SHR.
• These findings offer insights into differential vascular reactivity in hypertension.