Proceedings of The Physiological Society

University of Oxford (2011) Proc Physiol Soc 23, PC238

Poster Communications

Blood pressure increased dramatically in hypertensive rats after left hemisphere lesions with 6-OHDA

I. Banegas1, I. Prieto1, A. Segarra1, R. Durán2, F. Vives2, F. Alba2, J. Luna3, R. Wangensteen1, M. Ruiz-Bailén4, M. Ramírez1

1. Unit of Physiology. Department of Health Sciences., University of Ja

Plasma angiotensinase activity, nitric oxide and systolic blood pressure (SBP) were differently affected after unilateral intrastriatal injection of 6-hydroxydopamine (6-OHDA), depending on the brain hemisphere injured. Moreover, normotensive and hypertensive rats responded differently suggesting an asymmetry in the organization of the autonomic nervous system of the vessels(1,2). The aim of the study was to investigate the evolution with time of SBP and heart rate (HR) after nigrostriatal lesions in normotensive and hypertensive rat strains. Unilateral depletions of brain dopamine were performed by injecting 4 μl of 6-OHDA (8 mg dissolved in 1 ml of cold saline with 0.02% ascorbic acid to inhibit oxidation) into the left or right striatum of normotensive and hypertensive rats(1) under anesthesia (pentobarbital, 50 mg/kg, i.p.). 4 μl of saline with 0.02% ascorbic acid, instead of 6-OHDA, was unilaterally injected in control (sham) groups(1). SBP and heart rate (HR) were measured in un-anesthetised animals 10 and 3 days before administration of 6-OHDA or saline and 3 and 25 days after treatment. All experimental procedures were performed according to the European Union Guidelines to the Care and Use of Laboratory Animals and approved by the Ethical Committee of the University of Jaén. In normotensive rats, at the end of study, SBP increased significantly from pre-lesioned values in left-lesioned animals but no differences were observed in right-lesioned or sham groups. Before sacrifice, there was a significant reduction from pre-lesion values in HR. In hypertensive animals, there was a highly significant increase of SBP in left-lesioned and sham left rats and no differences were observed in both right groups. Regarding HR, except a slight increase in right-lesioned, no differences were observed throughout the study in the other groups. The present results represent direct experimental evidence for an asymmetrical cardiovascular response to unilateral brain lesions, suggesting that left injury may have a worst prognosis.

Where applicable, experiments conform with Society ethical requirements