No abstract

The literature is extensive on how hypertension affects the morphology and function of the central nervous system (CNS) and is being focused on multiple organ damage involving the kidneys, heart, endothelium and retina. Hypertension damage to the peripheral nervous system is less explored in the literature. We have previously shown morphometric alterations in large and small caliber myelinated fibers of nerves in the adult spontaneously hypertensive rat (SHR). However, the functional correlation of these findings has not been explored. We performed an electrophysiological investigation of hind limb nerves in SHR of both genders in different ages. Normotensive Wistar-Kyoto (WKY) rats were used as controls. Electrophysiological recordings and determination of motor (MCV) and sensory (SCV) nerve conduction velocity were performed in the same animals at four different ages: 5, 8, 20 and 40 weeks after birth. Comparisons were made between ages, genders and animal strain. We showed a continuous body weight increase in adult life in all animals studied. MCV got stable at 20-week old hypertensive animals and continued to increase in normotensive ones. The SCV was constant between the ages of 20 and 40 weeks old in female SHR and decreased in male SHR while it continued to increase in WKY animals. The electrophysiological investigation of the nerves in WKY and SHR from both genders and different ages, associated with morphological and morphometric data from the literature suggest that hypertension affects the nerve function and might corroborate the development of a peripheral neuropathy.

Previous results from our laboratory have shown morphological alterations on the sural nerves of female spontaneously hypertensive rats (SHR), mainly on the small myelinated fibers but there are no investigations on the functional significance of these alterations. Also, there are no reports on nerve functional differences between genders and age, particularly on the SHR. The present study investigated the alterations on the electrophysiological parameters of the sciatic nerves of male and female SHR with 5 and 8 weeks of age, compared to their normotensive controls WKY. After direct measurements of arterial pressure (cuff tail method), rats were anesthetized and electroneuromyographic studies were performed with the aid of a Keypoint® 4, Dantec‐Medtronic® equipment. Body weight and sensory and motor conduction velocities were significantly higher in older animals, for both genders and strains. Nevertheless, blood pressure values were similar between genders and strains, indicating that the SHR animals have not became hypertensive in the ages studied. The increase in the conduction velocity values reflects the nerve fibers growth that follows the animals aging.