M Ubeda — Page 2 | PubMed Health

PubMed1985

Normal hemodynamic parameters in conscious Wistar rats.

The evolution of different hemodynamic parameters with ponderal growth has been studied in conscious Wistar rats. The thermodilution method has been used to determine cardiac output and related variables. The results suggest that, between animal weight and the different hemodynamic parameters, there is a direct proportional relationship to blood volume, mean arterial pressure, cardiac output, stroke volume and total peripheral resistance, and an indirect proportional relationship to heart rate, cardiac index and stroke volume index. Body weight, therefore, plays a major role in hemodynamic determination, this having to be kept in mind when designing the experiment.

Animals↗

PubMedDate not supplied

Role of renin-angiotensin and sympathetic nervous systems in the chronic phase of two-kidney, one-clip hypertension in rats.

The purpose of the present study was to examine the role of the renin-angiotensin and the sympathetic nervous systems during the chronic phase (greater than 16 weeks) of two-kidney, one-clip hypertension in conscious unrestrained rats. During this phase, the mean arterial pressure (MAP) (p less than 0.001) and plasma angiotensin II (31.9 +/- 1.5 to 125.8 +/- 19.9 pg/ml, p less than 0.005) were significantly increased as compared to normotensive group. Converting enzyme inhibition by captopril produced a significant decrease of MAP (181.2 +/- 8.2 to 140.0 +/- 5.5 mmHg, p less than 0.001). This hypotensive response was similar when aprotinin (a Kallikrein inhibitor) and captopril were infused simultaneously. Alpha 1-adrenergic receptor blockade by phenoxybenzamine (POB) significantly decreased but did not normalize MAP (179.8 +/- 12.4 to 135.8 +/- 10.4 mmHg, p less than 0.001). However, when infused after POB, captopril induced a further decrease of MAP to 86.7 +/- 9.4 mmHg (p less than 0.001). This MAP level was not different from that found in normotensive rats after infusion of the two drugs (83.2 +/- 5.3 mmHg). These results suggest that both the renin-angiotensin system and the sympathetic nervous system, by activating peripheral alpha 1-adrenergic receptors, maintain the high blood pressure during the chronic phase (greater than 16 weeks) of two-kidney, one-clip hypertension in conscious rats.

Angiotensin II↗