Increased nitric oxide synthase mRNA expression in the renal medulla of water-deprived rats.
Increased nitric oxide synthase mRNA expression in the renal medulla of water-deprived rats.


BACKGROUND
Experiments were performed to investigate whether renal nitric oxide synthase (NOS) mRNA and protein expression are responsive to the alteration of body volume.


METHODS
Four days of water deprivation (WD) was initiated in 16 male Wistar rats, and 16 normal rats (NC) served as the control group. Neuronal NOS (nNOS), endothelial NOS (eNOS), and inducible NOS (iNOS) mRNAs and immunoreactivity were measured by reverse transcription-polymerase chain reaction (RT-PCR) followed by Southern blot hybridization and immunohistochemistry, respectively. Plasma angiotensin II, vasopressin, and atrial natriuretic peptide (ANP) concentrations were measured by radioimmunoassay.


RESULTS
The four-day WD increased plasma sodium and osmolality levels, but severely decreased daily urine sodium excretion and urine volume. Plasma angiotensin II and vasopressin concentrations were increased, but the plasma ANP level was significantly decreased in WD rats. nNOS, eNOS, and iNOS mRNA levels were increased by 5.2-, 3.3-, and 3. 4-fold in the outer medulla and 1.7-, 1.5-, and 1.8-fold in the inner medulla, whereas no significant difference was found in the renal cortex of WD rats as compared with NC rats. Additionally, immunohistochemistry revealed that the immunostaining intensity of nNOS, eNOS, and iNOS was clearly enhanced in the medullary thick ascending limb, proximal straight tubule, inner medullary collecting duct, and proximal convoluted tubule in WD rats. Kidney angiotensin II content as well as renin mRNA levels in renal cortex, outer medulla, and inner medulla in WD rats were apparently increased.


CONCLUSIONS
Our results indicate that the increases of nNOS, eNOS, and iNOS synthesis in the kidney, particularly in the renal medulla, may have a role in the adaptation of renal function to volume depletion in the face of an increase of systemic and intrarenal vasoconstrictive substances.
Shin
S J
SJ
Department of Clinical Pathology, Institute of Medicine, Kaohsiung Medical University, Taiwan.
Lai
F J
FJ
Wen
J D
JD
Lin
S R
SR
Hsieh
M C
MC
Hsiao
P J
PJ
Tsai
J H
JH
D000804:Angiotensin II / Q000032:analysis / Q000097:blood / Q000235:genetics; D000818:Animals; D015139:Blotting, Southern; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology; D007672:Kidney Cortex / Q000201:enzymology; D007679:Kidney Medulla / Q000737:chemistry / Q000201:enzymology*; D008297:Male; D019001:Nitric Oxide Synthase / Q000235:genetics*; D052248:Nitric Oxide Synthase Type I; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D012083:Renin / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014868:Water Deprivation / Q000502:physiology*
D012333:RNA, Messenger; D000804:Angiotensin II; D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; C496322:Nos1 protein, rat; C496318:Nos2 protein, rat; C496316:Nos3 protein, rat; D012083:Renin