Integrative pattern of vasomotor efficiency in SHR during ontogenesis

Area of Science:

• Cardiovascular Physiology
• Pharmacology

Background:

• Controversial data exists regarding cardiovascular system function in Spontaneously Hypertensive Rats (SHR).
• Variability in studies may stem from differences in vascular segments, studied areas, or animal age.
• Blood pressure (BP) is an integrated vascular system response, stabilized in SHR until one year of age.

Purpose of the Study:

• To investigate age-dependent changes in blood pressure regulation in male SHR compared to Wistar rats.
• To assess the cardiovascular system's integrated response to noradrenaline and acetylcholine challenges across different ages.

Main Methods:

• Male SHR and age-matched Wistar rats (3, 5, 9, 17, and 52 weeks old) were used.
• Basal blood pressure was measured.
• Responses to intravenous injections of noradrenaline and acetylcholine at varying doses were recorded.

Main Results:

• Significant basal BP differences between SHR and Wistar rats emerged at 9 weeks and persisted until 52 weeks (189.6±11.9 vs. 117.3±6.9 mm Hg).
• Enhanced BP increase to noradrenaline was observed in SHR from 9 weeks of age.
• Enhanced hypotensive response to acetylcholine in SHR was noted from 17 weeks of age, persisting to 52 weeks.

Conclusions:

• The cardiovascular system of SHR exhibits an enhanced response to noradrenaline starting from 9 weeks of age.
• The response to acetylcholine is augmented in SHR not before 17 weeks of age.
• These age-dependent variations in SHR cardiovascular reactivity are critical for understanding hypertension progression.