Pengaruh durasi pemberian kombinasi ekstrak akar kucing acalypha indica linn dan pegagan centella asiatica terhadap perubahan aktivitas spesifik glutation peroksidase dalam ginjal tikus pascahipoksia = The effect of duration of combined akar kucing acalypha indica linn and pegagan centella asiatica extract supplementation on glutathione peroxidase spesific activity of post hypoxic mice kidneys