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Hemodynamic characteristics of conscious deoxycorticosterone acetate hypertensive rats
Insights
Deoxycorticosterone acetate (DOCA) hypertension in rats involves increased cardiac output and elevated vasoconstrictor tone, particularly in the superior mesenteric and hindquarter areas. This sympathetic tone elevation is crucial for maintaining DOCA-induced hypertension.
Area of Science:
- Physiology
- Cardiovascular Research
- Hypertension Pathophysiology
Background:
- Deoxycorticosterone acetate (DOCA)-salt hypertension is a model for studying elevated blood pressure.
- Understanding the underlying mechanisms of DOCA hypertension is crucial for developing effective treatments.
Purpose of the Study:
- To investigate regional blood flow and sympathetic vasoconstrictor tone in DOCA-hypertensive rats.
- To elucidate the roles of cardiac output and sympathetic tone in sustaining hypertension.
Main Methods:
- Chronic implantation of electromagnetic flow probes in major arteries of DOCA-treated and control rats.
- Measurement of terminal aortic pressure via femoral artery catheter.
- Pharmacological assessment of sympathetic tone using hexamethonium and vasopressin antagonists.
Main Results:
- DOCA hypertensive rats showed increased superior mesenteric and renal blood flow compared to controls.
- Cardiac output was elevated in DOCA hypertensive rats.
- Substantial sympathetic vasoconstrictor tone was observed in mesenteric and hindquarter areas of DOCA rats, unlike in controls.
Conclusions:
- Hypertension in DOCA rats is sustained by increased cardiac output and elevated vasoconstrictor tone.
- The elevation of sympathetic tone, induced by DOCA and salt, is indispensable for DOCA hypertension.
Abstract:
An electromagnetic flow probe was chronically implanted around the common carotid, superior mesenteric, or renal artery or the terminal aorta in deoxycorticosterone acetate (DOCA) hypertensive rats (prepared with DOCA and saline after uninephrectomy) and uninephrectomized control rats. A catheter for pressure measurement was inserted into the terminal aorta through a femoral artery. At rest the carotid and hindquarter (measured at the terminal aorta) blood flows in DOCA hypertensive rats were similar to the respective, corresponding values in normal rats with intact bilateral kidneys. The group mean of superior mesenteric flow was about 70% and that of renal flow about 40% larger than in normal rats. Cardiac output was estimated to be greater in DOCA hypertensive rats than in normal rats. In uninephrectomized control rats, superior mesenteric flow was larger than in normal rats to such an extent that an increase in cardiac output was assumed as in DOCA hypertensive rats, but renal flow was normal (about twice the unilateral renal flow in normal rats). Estimation of regional sympathetic vasoconstrictor tone from the decrease in peripheral resistance with hexamethonium and vasopressin antagonist revealed a substantial tone also in the superior mesenteric and hindquarter areas, where the tone was estimated to be almost absent in normal rats and uninephrectomized rats. It is suggested that hypertension in DOCA hypertensive rats is sustained by an increase in cardiac output and an elevation of vasoconstrictor tone in resistance vessels. Since increase in cardiac output appears to be similarly present in uninephrectomized control rats, the elevation of sympathetic tone due to administration of DOCA and salt seems to be indispensable for DOCA hypertension.