Baroreceptor control of vasopressin-producing cells in streptozotocin diabetic rats.
Electrical activities of the vasopressin (AVP)-producing cell in the supraoptic nucleus of the streptozotocin diabetic (STZ-DM) rat were recorded extracellularly and compared with those in the control rat. Higher hematocrit (45.3 +/- 0.5%, mean +/- SE) and lower mean blood pressure (MBP) (89.5 +/- 2.1 mmHg) suggested that STZ-DM rats were hypovolemic and hypotensive. The mean discharge rates of AVP cells were 15.2 +/- 3.1 Hz (STZ-DM) (p < 0.05 vs. control) and 8.8 +/- 0.8 Hz (control), respectively. Pressor and depressor responses were caused by phenylephrine (1.5 and 2.9 micrograms/kg, i.v.) and nitroprusside (1.5 micrograms/kg, i.v.), respectively, during the recording the AVP cells. Pressor and depressor responses linearly (STZ-DM; gamma = -0.7071, control; gamma = -0.9262) decreased and increased the discharge activity of the cells in both experimental groups, respectively. The MBP-neuronal activity relationship in STZ-DM did not differ statistically from that in the control. These results suggest that cardiovascular regulation of AVP release is well retained in STZ-DM rats.
Department of Physiology, Niigata University School of Medicine, Japan.
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Akaishi
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Homma
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D001127:Arginine Vasopressin / Q000096:biosynthesis*; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism*; D008297:Male; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D009599:Nitroprusside / Q000494:pharmacology; D010656:Phenylephrine / Q000494:pharmacology; D011311:Pressoreceptors / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D013495:Supraoptic Nucleus / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*
D001127:Arginine Vasopressin; D009599:Nitroprusside; D010656:Phenylephrine