Lack of circadian change of concentration of C-type natriuretic peptide in rabbit aqueous humor

Arquivos Brasileiros de Oftalmologia

Augusto Paranhos Jr.²  Koji Okada¹  Paulo Augusto De Arruda Mello¹  João Antônio Prata Jr.¹  Douglas Gregory¹ 

[1],Universidade Federal de São Paulo Setor de Glaucoma São Paulo SP ,Brasil

关键词: Natriuretic agents;    Cyclic GMP;    Aqueous humor;    Intraocular pressure;    Ocular physiology;    Glaucoma;    Natriuretic peptide;    C-type;    Circadian rhythm;    Rabbits;    Natriuréticos;    GMP cíclico;    Humor aquoso;    Pressão intra-ocular;    Fisiologia ocular;    Glaucoma;    Peptídeo natriurético tipo C;    Ritmo circadiano;    Coelhos;   

DOI  :  10.1590/S0004-27492006000500018

来源: SciELO

【 摘 要 】

PURPOSE: To determine whether there is a circadian change of the concentration of C-type natriuretic peptide (CNP) in rabbit aqueous humor. METHODS: Forty-one male white New Zealand rabbits were submitted to a 12 h light and 12 dark lighting schedule; lights on was at 0 h, lights off at 12 h. C-type natriuretic peptide was assayed at 3 light (2 h, 6 h and 10 h) and 3 dark (14,18 and 22 h) times. All groups consisted of four animals but two had more animals to increase the power of tests (6 h, n=12; 22 h, n=13). Dependence between the two eyes was tested by Pearson's correlation. The mean of two eyes was considered for analysis. Differences in concentration in pg/200 ml were evaluated by one-way ANOVA, t test and COSINOR analysis. RESULTS: There were no significant differences between the 6 analyzed groups (one-way ANOVA p=0.157). Pooled into two groups (light and dark), the C-type natriuretic peptide concentration of the light group was lower, 2.626±0.92 pg/200 ml compared with the dark group 3.02±1.16 pg/200 ml but did not reach a significant difference (t test; p=0.23). COSINOR analysis was not statistically significant (R%=7.72 p=0.209). CONCLUSION: These data demonstrate that the concentration of CNP in aqueous humor did not show a statistically significant circadian change in rabbits entrained to a 12 h light: 12 h dark lighting schedule.

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