Hypothalamic and plasma total nitrate/nitrite concentrations in spontaneously hypertensive rats

Abstract

SUMMARYStable end-products of nitric oxide (NO) metabolism, nitrates and nitrites, were measured in hypothalamic extracts and plasma samples of Okamoto spontaneously hypertensive (SH) rats. The mean total nitrate/nitrite concentration was significantly lower in the hypothalami of SH rats compared with the normotensive Wistar Kyoto (WKY) control animals (P < 0-01). In contrast, their plasma concentrations were significantly higher (P < 0.05). These results indicate that the hypertensive state in SH rats is associated with a diminished production of hypothalamic NO, while the raised plasma nitrate/nitrite levels could reflect an increased compensatory endothelial NO synthase activity in these animals compared with the WKY controls.

Endothelial Nitric Oxide Synthase-Independent Release of Nitric Oxide in the Aorta of the Spontaneously Hypertensive Rat

“…The present study confirms that, compared with its normotensive control, the WKY, the SHR has a higher concentration of nitrate/nitrite in both plasma and aorta (Alaghband-Zadeh et al, 1996;Wu and Yen, 1999). Nitrate and/or nitrite are the logical source of the NOS-independent NO, since they are the metabolic end-products of the NO-pathway that can be reduced to again form bioactive nitrogen oxides, including NO (Lundberg et al, 2008).…”

Nitric oxide: Involvement in the nervous control of cardiovascular function

“…In SHR, the NOS activity in the hypothalamus was also found to be lower, as compared with the norm [87]. The amount of nNOS mRNA in the hypothalamus and RVLM of rats with central mineralocorticoidinduced hypertension was shown to be significantly reduced, as compared with that in normotensive rats [76].…”

Enhanced Depressor Response to Endothelial Nitric Oxide Synthase Gene Transfer into the Nucleus Tractus Solitarii of Spontaneously Hypertensive Rats

“…In contrast, nNOS activity in the dorsal medulla, as indicated by L-citrulline formation, has been shown to be significantly depressed in SHR compared to that of WKY (18). The decreased NOS activity measured by content of nitrite and nitrate has also been demonstrated in the hypothalamus of SHR (19). These results suggest that the L-arginine-NO pathway is impaired in SHR, possibly due to a post-transcriptional abnormality (4).…”