Acute And Chronic Stressors Differentially Affect Myogenic Reactivity Of Mesenteric Arteries In Spontaneously Hypertensive Male Rats

Acute and chronic stressors contribute differentially to the development of cardiovascular diseases involving blood pressure, vessel reactivity, and stress hormones. To investigate these mechanisms, we used restraint (acute ‐ 1 hr) and colony environmental housing (chronic ‐ 3 months) to examine changes in: systolic blood pressure (SBP), vessel reactivity to intraluminal pressure increases (myogenic reactivity, MYO), and plasma norepinephrine (NE) as an index for sympathetic nervous system (SNS) activity. We hypothesized that acute restraint stress will increase SBP, MYO of resistance‐sized mesenteric arteries, and plasma NE more compared to chronic environmental stress. Age‐matched adult SHR males were subjected to weekly restraint stress (n=7; 3 days/wk ‐ 1 month) or continuous colony housing stress (n=9) as compared to non‐stressed controls (n=7) in standard caging. Blood pressure was measured weekly via tail cuff, mesenteric artery reactivity was determined using a pressurized arteriograph, and plasma NE was assayed by HPLC. Acute restraint stressed animals exhibited increased MYO of mesenteric arteries compared to chronically stressed and control animals (p<0.05) possibly due to physiological adaptation in the colony housed rats. In conclusion, acute restraint stress may lead to increased SNS activity that results in increased MYO of resistance vessels involved in regulating blood pressure.