Article date: February 1980
By: SHEILA A. DOGGRELL, LYNN VINCENT in Volume 71, Issue 2, pages 557-567
Strips of guinea‐pig gall bladder readily accumulate 3H following incubation in the presence of 5 times 10−8m (‐)‐[3H]‐noradrenaline. This accumulation was reduced by lowering the incubation temperature (from 37° to 23°C), by cocaine (10−6m), by nortriptyline (10−8, 10−6 and 10−4m) and following incubation of the tissues with 6‐hydroxydopamine (10−3m for 3 h). At 10−6m, (‐)‐noradrenaline and (‐)‐adrenaline, but not (‐)‐isoprenaline, inhibited the accumulation of 3H.
Following preloading of strips of guinea‐pig gall bladder with 3.6 times 10−7m (‐)‐[3H]‐noradrenaline for 1 h, the spontaneous overflow of 3H was observed. Cocaine (10−4m), nortriptyline (10−6m), (‐)‐isoprenaline (10−5m), acetylcholine (10−5m) and adenosine 5′‐triphosphate (ATP, 10−4m) had no effect on the spontaneous overflow of 3H. KCl (10−1m), (‐)‐noradrenaline (10−5m), (‐)‐adrenaline (10−5m), and tyramine (10−5m) increased the overflow of 3H. These results illustrate similar characteristics of the guinea‐pig gall bladder to other noradrenergically‐innervated tissues in accumulating and releasing 3H following incubation in the presence of [3H]‐noradrenaline.
Following incubation in the presence of 3.6 times 10−7m (‐)‐[3H]‐noradrenaline, field stimulation, at 5 Hz, of strips of gall bladder, in the absence or presence of 10−6m atropine, increased the overflow of 3H and, simultaneously, induced contractions. The contractile responses to 5 Hz were smaller in the presence than in the absence of 10−4m lignocaine. Lignocaine (10−4m) reduced the overflow of 3H evoked by field stimulation at 5 Hz. It is suggested that the contractile responses to 5 Hz are due to nerve stimulation and that the increased overflow of 3H is due to the stimulation of noradrenergic nerves.
The overflow of 3H evoked by field stimulation at 5 Hz was unaltered and increased by propranolol (10−6m) and phentolamine (10−6m), respectively. Clonidine (5 times 10−5m) had no effect in the absence but reduced the amount of 3H which overflowed in response to field stimulation at 5 Hz in the presence of 10−6m atropine. The contractile responses to field stimulation at 5 Hz were reduced by phentolamine (10−6m) or clonidine (5 times 10−6, 10−5 and 5 times 10−5m) whether or not atropine (10−6m) was present. These results illustrate the presence of postsynaptic α‐adrenoceptors and suggest the presence of presynaptic α‐adrenoceptors in the gall bladder of the guinea‐pig.
Strips of guinea‐pig gall bladder readily accumulate 3H following incubation in the presence of 5 times 10−8m (‐)‐[3H]‐noradrenaline. This accumulation was reduced by lowering the incubation temperature (from 37° to 23°C), by cocaine (10−6m), by nortriptyline (10−8, 10−6 and 10−4m) and following incubation of the tissues with 6‐hydroxydopamine (10−3m for 3 h). At 10−6m, (‐)‐noradrenaline and (‐)‐adrenaline, but not (‐)‐isoprenaline, inhibited the accumulation of 3H.
Following preloading of strips of guinea‐pig gall bladder with 3.6 times 10−7m (‐)‐[3H]‐noradrenaline for 1 h, the spontaneous overflow of 3H was observed. Cocaine (10−4m), nortriptyline (10−6m), (‐)‐isoprenaline (10−5m), acetylcholine (10−5m) and adenosine 5′‐triphosphate (ATP, 10−4m) had no effect on the spontaneous overflow of 3H. KCl (10−1m), (‐)‐noradrenaline (10−5m), (‐)‐adrenaline (10−5m), and tyramine (10−5m) increased the overflow of 3H. These results illustrate similar characteristics of the guinea‐pig gall bladder to other noradrenergically‐innervated tissues in accumulating and releasing 3H following incubation in the presence of [3H]‐noradrenaline.
Following incubation in the presence of 3.6 times 10−7m (‐)‐[3H]‐noradrenaline, field stimulation, at 5 Hz, of strips of gall bladder, in the absence or presence of 10−6m atropine, increased the overflow of 3H and, simultaneously, induced contractions. The contractile responses to 5 Hz were smaller in the presence than in the absence of 10−4m lignocaine. Lignocaine (10−4m) reduced the overflow of 3H evoked by field stimulation at 5 Hz. It is suggested that the contractile responses to 5 Hz are due to nerve stimulation and that the increased overflow of 3H is due to the stimulation of noradrenergic nerves.
The overflow of 3H evoked by field stimulation at 5 Hz was unaltered and increased by propranolol (10−6m) and phentolamine (10−6m), respectively. Clonidine (5 times 10−5m) had no effect in the absence but reduced the amount of 3H which overflowed in response to field stimulation at 5 Hz in the presence of 10−6m atropine. The contractile responses to field stimulation at 5 Hz were reduced by phentolamine (10−6m) or clonidine (5 times 10−6, 10−5 and 5 times 10−5m) whether or not atropine (10−6m) was present. These results illustrate the presence of postsynaptic α‐adrenoceptors and suggest the presence of presynaptic α‐adrenoceptors in the gall bladder of the guinea‐pig.
DOI: 10.1111/j.1476-5381.1980.tb10973.x
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