Vah95ab

Each rat was implanted with a chronic indwelling catheter into the right jugular vein under i.m. droperidol (2 mg/kg)/fentanyl (0.04 mg/kg) anesthesia, described in detail elsewhere (Harris et al., 2008 ; LeSage et al., 2002 (link)). The catheter was externalized between the scapulae and attached to a vascular-access harness (VAH95AB, Instech Laboratories, Plymouth Meeting, PA) that allowed connection to a fluid swivel via a tether for nicotine administration. Animals were allowed to recover for at least four days after surgery, during which time they received daily i.v. infusions of heparinized saline and ceftriaxone (5.25 mg) and s.c. injections of buprenorphine (0.1 mg/kg; first two days only) for analgesia. Infusions of methohexital (0.1 ml, 10 mg/ml, i.v.) were administered to check patency at the end of the study and on occasions when malfunctions were suspected. If the catheter became occluded prior to the dose-reduction protocol (see 2.6), another catheter was implanted into the contralateral jugular or ipsilateral femoral vein. If catheter failure occurred during the dose-reduction protocol, the rat was excluded from the study.

Each rat was implanted with a chronic indwelling catheter into the right jugular vein under i.m. ketamine (75–90 mg/kg)/dexmedetomidine (0.25 mg/kg) anesthesia, described in detail elsewhere (Harris et al., 2008 (link); Lesage et al., 2002 (link)). The catheter was externalized between the scapulae and attached to a vascular-access harness (VAH95AB, Instech Laboratories, Plymouth Meeting, PA) that allowed connection to a fluid swivel via a tether for drug administration. Animals were allowed to recover for at least four days after surgery, during which time they received daily i.v. infusions of heparinized saline and ceftriaxone (5.25 mg) and s.c. injections of buprenorphine (0.05 mg/kg; first two days only) for analgesia. Infusions of methohexital (0.1 ml, 10 mg/ml, i.v.) were administered weekly on Fridays after behavioral testing to check catheter patency. If a catheter became occluded, another catheter was implanted into the ipsilateral femoral vein. Failure of this second catheter resulted in the removal of the animal from the study.

Each rat was implanted with a chronic indwelling catheter into the right jugular or femoral vein under ketamine (100.00 mg/kg, i.m.)/dexmedetomidine (0.25 mg/kg, i.m.) anesthesia, with atipamezole (1.00 mg/kg, s.c.) for reversal following surgery. The catheter was externalized between the scapulae and attached to a vascular-access harness (VAH95AB, Instech Laboratories, Plymouth Meeting, PA) that allowed connection to a fluid swivel via a tether for nicotine administration. Animals were allowed to recover for at least four days after surgery, during which time they received daily i.v. infusions of ceftriaxone (5.00 mg/day) and buprenorphine (0.10 mg/kg, s.c.; first 2 days only) for analgesia. When necessary, catheter patency was verified using methohexital (1.50 mg, i.v.). Catheter occlusion, as seen by failure to exhibit signs of anesthesia, resulted in the implantation of a new catheter in the left femoral vein or exclusion from the study if the second catheter failed. The total number of animals that received a femoral implant during the course of the investigation was 4, out of 25.