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NOX2 is the primary source of superoxide in the macula densa in angiotension II induced hypertension
Author(s) -
Zhang Rui,
Lu Deyin,
Fu Yiling,
Juncos Luis,
Liu Ruisheng
Publication year - 2009
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.23.1_supplement.lb147
Subject(s) - macula densa , nox4 , nadph oxidase , chemistry , angiotensin ii , tubuloglomerular feedback , superoxide , medicine , endocrinology , angiotensin ii receptor type 1 , receptor , nad(p)h oxidase , nitric oxide , renin–angiotensin system , receptor antagonist , antagonist , reactive oxygen species , biochemistry , biology , blood pressure , enzyme , renal function
Tubuloglomerular feedback (TGF) is one of the main mechanisms that regulate the renal microcirculation, NaCl excretion, and ultimately blood pressure. Superoxide (O − 2 ) in the macula densa (MD) enhances TGF by scavenging nitric oxide. MD expresses NOX2 and NOX4 isoforms of NAD(P)H oxidase. We hypothesize that NOX2 is the primary isoform for O − 2 in angiotensin II (Ang II) induced hypertension. MD like cell line, MMDD1, was used. O − 2 was measured using lucigenin chemiluminescence with a luminometer and expressed by units/min/10 6 cells. To measure whether Ang II induces O − 2 production in MMDD1 cells, we stimulated the cells with Ang II (10 6 M) for 30 min. O − 2 production increased from 198.4 ± 14.7 to 447.6 ± 21.2 units/min/10 5 cells. To determine if the Ang II induced O − 2 is mediated through AT1 or AT2 receptors, we used specific receptor antagonists. In the presence of AT1 receptor antagonist losorten (10 −6 M), O − 2 was from 198.4 ± 14.7 to 214.7 ± 35.4 unit/min/10 6 cells. In the presence of AT2 receptor antagonist PD‐123319 (10 −6 M), O − 2 was from 198.4 ± 14.7 to 435.1 ± 25.3 unit/min/10 5 cells. To study which NOX is the primary source of Ang II induced O − 2 , we knocked down NOX2 or NOX4 with siRNA and measured O − 2 . In the cells treated with siRNA‐NOX2, Ang II induced O − 2 was from 163.9 ± 32.6 to 239.5 ± 51.8 unit/min/10 5 cells. In the cells treated with siRNA‐NOX4, O − 2 was from 117.2 ± 19.3 to 422.8 ± 21.7 unit/min/10 5 cells. Scramble treated cells are not different in O − 2 when compared with control. Conclusions Ang II induces O − 2 production in MMDD1 cells mediated via AT1 receptors. NOX2 is the primary source of in Ang II induced O − 2 .