COMPARISONS OF NEUROTRANSMITTER CONCENTRATIONS IN THE SYNAPTOSOMAL PREPARATION OF THE NORMOTENSIVE AND HYPERTENSIVE RAT URINARY-BLADDER

Synaptosome-rich fractions were prepared from tissue homogenate of the urinary bladder of the spontaneously hypertensive rat and normotensiv e Wistar-Kyoto rat by differential centrifugation (1000 X g, 17 000 X g and 100 000 X g) with discontinuous sucrose gradient. Synaptosomal a cetylcholine, norepinephrine, epinephrine and dopamine were measured b y the method of high-performance liquid chromatography. The respective neurotransmitter concentrations for the normotensive rats were 300.4 +/- 30.1, 962.8 +/- 58.5, 617.3 +/- 59.8, and 1354.8 +/- 144.2 pmol/mg synaptosomal protein. For the hypertensive rats, the acetylcholine co ncentration (203.8 +/- 23.0 pmol/mg protein) was significantly lower ( P < 0.05), while the norepinephrine, epinephrine and dopamine concentr ations (1459.0 +/- 180.3, 971.3 +/- 62.2, and 2161.0 +/- 243.4 pmol/mg protein, respectively) were significantly higher (P < 0.05 for all) t han those of the normotensive rats. In conclusion, it has been demonst rated that the vesicle-bound catecholamines in the synaptosome-rich fr action of the urinary bladder were significantly increased in hyperten sive rats. On the contrary, the synaptosomal acetylcholine concentrati on was significantly decreased. These findings are suggestive of incre ased sympathetic innervation and decreased parasympathetic innervation in the urinary bladder of the spontaneously hypertensive rat.