## 4 Results  
The animals quickly recovered from surgery and began walking on all four legs. The bulbocavernosus reflex test conducted with a pull on the Foley catheter produced a moderate anal contraction. DBWS was conducted during the early and late testing periods. Early tests in the conscious animal used the two bipolar sets of electrodes with simultaneous pulses at 40  
Figure 3: Helical-wire hook electrode implantation in the first minipig with a needle and sutures, and in the second and third minipigs with imprication and sutures. (**A**) In the first minipig, one electrode is shown after implantation with sutures in place and a second electrode is being implanted with a needle in a more medial–dorsal location (white arrow). (**B**) Looping of four electrode leads for strain relief is shown in the abdominal cavity. (**C**) The implication method of electrode implantation is shown for the last two animals. The electrode is over the bladder wall prior to implantation. (**D**) The area of the bladder wall ventral to the trigone is implanted with the four imbricated electrodes (white arrows). Hz. The stimulating current, however, was limited to 10 mA due to abdominal, leg, and anal contractions, and animal discomfort; bladder contractions were not induced. Therefore, general anesthesia was used during testing in the late period to prevent any animal discomfort. Responses to stimulation at 10 to 40 mA induced stronger skeletal muscle contraction and no or slight vesical pressure responses. Representative records for the 60 mA stimulation current for each of the three animals on PO Day 9 are shown in Figure 4: vessel pressure increased rapidly at the start of stimulation, and this was attributed to abdominal pressure changes caused by abdominal wall contractions. Continued stimulation was associated with a slow but significant increase in the vesical pressure to a plateau value, which was attributed to vesical wall contraction. The 60 mA current also caused strong contraction of the legs and anal sphincter. Representative responses for all stimulation tests conducted at 40 Hz using all four electrodes, at an average filling volume of 188 mL (\(\pm\)29 mL), are shown in Table 1. Moderate vesical wall contractions were observed only during the late period, when anesthesia and high stimulating currents were used. Use of only a single set of electrodes or stimulation at 20 Hz produced less vesical wall response (results not shown in Table 1). These tests, however, were conducted at the end of the protocol and bladder fatigue may have been a factor in decreased responses. None of the stimulation tests induced voiding, even after removal of the Foley catheter, so the voiding efficiency was 0%. Daily animal care included disposal of copious amounts of urine from the Foley bag, and dipstick tests indicated no signs of urinary tract infection. Animals were sacrificed on \begin{table}
\begin{tabular}{l c c c} \hline \hline  & **Initial Bladder Pressure** & **Bladder Pressure Increase Due** & **Bladder Pressure Increase due** \\  & **(cm H\({}_{2}\)O)** & **to Abdominal Contractions** & **to Detrusor Contractions (cm H\({}_{2}\)O)** \\ \hline Pig \#1 & & & \\ \hline Early phase (no anesthesia) & 3 & 23 & 0 \\ Late phase (under anesthesia) & 15 & 33 & 6 \\ \hline Pig \#2 & & & \\ Early phase(no anesthesia) & 12 & 23 & 0 \\ Late phase (under anesthesia) & 13 & 22 & **28** \\ \hline Pig \#3 & & & \\ Early phase(no anesthesia) & 0 & 20 & 0 \\ Late phase (under anesthesia) & 22 & 7 & **26** \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Responses to 40 Hz four electrode stimulation at 10 mA in the conscious animal during early testing days (average values from postoperative days 4 and 7) and at 60 mA under anesthesia during the late testing days (average values from postoperative days 9 and 28) from the three minipigs. The important vesical wall contraction increases in pressure are highlighted in red.