Chronic local infusion into the renal artery of unrestrained rats

A method is described for providing chronic access to the right renal artery of unrestrained rats. It consists of insertion of a very thin (OD 0.2 mm) catheter into the right suprarenal artery of Wistar rats. The suprarenal artery originates from the right renal artery. After the cannula has been guided subcutaneously to the neck, it is connected to an Alzet osmotic minipump. The method has a success ratio of over 90% for periods up to 14 days. In the present study, we investigated the effects of catheter implantation on renal hemodynamics in uninephrectomized rats that were infused with saline for 2, 6, or 14 days. Values were compared with those obtained in control rats. Glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) were estimated from plasma clearances of 51Crethylenediaminetetraacetic acid and 125I-p-aminohippuric acid, respectively. Mean arterial pressure was between 107 +/- 2 and 116 +/- 2 mmHg in all animals. Neither GFR nor ERPF was influenced by catheter implantation. It is concluded that the method does not interfere with renal function.