Abstract
Our previous data obtained by cDNA microarray analysis and quantitative RT-PCR indicated that the arachidonic acid–leukotriene B4 (LTB4) may be up-regulated in the nucleus tractus solitarii (NTS), a pivotal region regulating arterial pressure, in the spontaneously hypertensive rat (SHR) compared to their progenitor strain, Wistar-Kyoto rat (WKY). In this study, we tested the functional significance of LTB4 in the NTS in regulating cardiovascular system. In radio-telemetered WKY LTB4 was microinjected into the NTS and cardiovascular parameters were monitored over one week. Although the arterial pressure (BP) did not change acutely, it increased gradually over 4 days (about 15 mmHg, n=5) demonstrating its pro-hypertensive effect. Heart rate and spontaneous baroreflex gain did not change. Power spectral analysis of BP demonstrated that three days post LTB4 injection the LF + VLF power of BP variability was increased (about 45%, n=5) indicative of raised sympathetic activity. We suggest that LTB4 in the NTS is affecting mechanisms controlling the set point of arterial pressure independent of alteration in baroreflex gain. Since LTB4 is known to be involved in inflammatory diseases, we propose a new hypothesis that inflammatory reactions in the NTS may lead to detrimental consequences for cardiovascular autonomic homeostasis resulting in neurogenic hypertension. British Heart Foundation funded research. [J Physiol Sci. 2008;58 Suppl:S59]
