AIM To investigate whether there is vasodilator nerve innervation in rat hind limb and what the nature of vasodilator nerve is. METHODS Wistar rats were treated with reserpine 1 mg?kg -1 ip at 24 h before experiment. The rats were pithed and the hind limb vascular bed was perfused with Krebs-Henseleite solution containing 1 mmol?L -1 phenylephrine at 2 ml?min -1 speed. The hind limb perfused pressure (HPP) as a main index was continuously recorded. Spinal cord electrical stimulation (SES) was repeatedly applied via an electrode at L 1～2 level of lumber vertebra. The various tool drugs were administered by iv or infusion by added to persusion solution. The data is expressed as decrease percentages of HPP increased by continuous infusion of phenylephrine. RESULTS HPP was increased from (5 7?1 5) to (21 6?3 7) kPa ( n =37) after phenylephrine perfusion. SES caused a fall of HPP in frequency dependent and voltage dependent manner. An optimum parameters of SES (10 Hz, 50 V and 1 msec) was selected to observe effects of various tool drugs on depressor response of HPP to SES. Tetrotodoxin (0 3 ?mol?L -1 ) abolished the effect completely. L NAME (10 ?mol?L -1 ), a NO synthase inhibitor, had no effect. Ganglion blocker arfonad (110 mg?kg -1 , iv, M R blocker atropine (10 ?mol?L -1 ), ? receptor blocker propranolol (1 ?mol?L -1 ) and P 1 receptor blocker aminophylline (10 ?mol?L -1 ) had also no effect. Glibenclamide (0 1 mmol?L -1 ), an ATP sensitive K + channel blocker, markedly abolished and slightly reversed the effect. CONCLUTION The nonadrenergic noncholinergic vasodilator nerve exists in rat hind limb and is not nitroxidergic or purinergic nerve. This nerve may be peptidergic nerve which releases some peptide such as CGRP and the major mechanism of vasodilatation probably activates the ATP sensitive K + channel.

Objective: To study the effect of docetaxet (DOC) combined with 4-AP on human breast can-cer MCF-7 cells and to explore whether 4-AP could strengthen the effect of docetaxel. Methods: MTT assays were performed to investigate the effect of docetaxel, 4-AP and the combination of them on the proliferation of MCF-7 cells. Flow cytometry was employed to detect cell cycles and cell apoptosis after the cells were stained by PI alone or by Annexin-V and PI. Results: Docetaxel could significantly inhibit the proliferation of MCF-7 cells in a dose- and time- dependent manner. 4-AP could inhibit the proliferation of MCF-7 cells and the inhibitory rates were 11.9%±1.7%, 42.1%±3.2%, and 44.2%±1.6% at 24h, 48h and 72h after adding 4-AP. Moreover 4-AP (5mmol/L) could strengthen the effect of docetaxel. 4-AP (25μmol/L) could increase the effect of Docetaxel. Docetaxel at 5μmol/L could significantly increase the percentage of cells at G_2/M (53.58%± 1.44% vs. 8.83%±0.44%, P<0.01) and decrease the percentage of cells at G_0/G_1 (11.48%±0.14% vs. 63.89%±0.98%, P<0.01), indicating that docetaxel blocked MCF-7 cells at G_2/M phase. 4-AP at 5mmol/L could in-crease the percentage of MCF-7 cells at G_0/G_1 and decrease the percentage of cells at G_2/M (0.42%±0.17% vs. 8.83%±0.44%, P<0.05). Docetaxel could significantly increase late apoptosis and death of MCF-7 cells af-ter treatment over 24h (from 6.97%±0.75% to 20.77%±0.75%, P<0.05). Docetaxel combined with 4-AP could increase early apoptosis rate from 4.60%±0.91% to 12.20%±0.82% (P<0.05) and could increase late apopto-sis rate and death rate from 4.60%±0.91% to 12.20%±0.82% (P<0.05). Conclusion: Both docetaxel and 4-AP can inhibit the proliferation of MCF-7 cells. Docetaxel can increase the percentage of cells at G_2/M phase and 4-AP can increase the percentage of cells at G_0/G_1 phase. 4-AP could strengthen the inhibitory effect of docetaxel on the proliferation of MCF-7 cells through inducing cell apoptosis.