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1

Enhanced pressor response to centrally administered vasopressin in WKY rats on high sodium diet

100%

Zera T., Ufnal M.

Acta Neurobiologiae Experimentalis

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2005

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vol. 65

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issue 2

145-150

EN

Four week old Wistar-Kyoto (WKY) rats were divided into two groups. The experimental group (n=7) was receiving a high sodium diet (3.28% Na+) and the control group (n=7) a normal sodium diet (0.22% Na+). After 8 weeks, subjects were chronically implanted with the lateral cerebral ventricle (LCV) cannulas and with the femoral artery catheters. Three series of experiments were carried out on the experimental and control groups. In each series mean arterial pressure (MAP) and heart rate (HR) were recorded for 10 min before and 30 min after the LCV infusion. In series 1 artificial cerebrospinal fluid (aCSF) was administered (2 mul/15 s). In series 2 AVP was infused (20 ng/2 mul aCSF/15 s). In series 3 V1a receptor antagonist (V1 ANT), d(CH2)5[Tyr(Me)2,Ala-NH29]AVP, was applied (80 ng/mul aCSF/15 s). There was no difference in baseline MAP and HR between the experimental and control groups. LCV infusion of aCSF had no effect on MAP and HR. LCV infusion of AVP produced a significant increase of MAP, which was greater in the group on the high sodium diet than in the group on normal sodium diet. The experimental group showed a longer hypertensive effect of centrally applied AVP in comparison to the control. LCV administration of V1 ANT did not exert a significant effect on circulatory parameters. These results suggest that the prolonged high sodium diet does not induce hypertension in WKY rats, but it enhances the pressor function of the central vasopressinergic system.

2

Centrally applied vasopressin prevents posthemorrhagic hypotension in WKY rats

100%

Ufnal M., Zera T.

Acta Neurobiologiae Experimentalis

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2002

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vol. 62

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issue 1

51

3

Exogenous hydrogen sulfide produces hemodynamic effects by triggering central neuroregulatory mechanisms

81%

Ufnal M., Sikora M., Dudek M.

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issue 3

382-388

EN

Recently, it was found that hydrogen sulfide (H2S) may serve as an important transmitter in peripheral organs as well as in the brain. The aim of the present study was to evaluate the possible function of H2S in the brain regulation of the circulatory system. Experiments were performed on conscious, male, Wistar-Kyoto rats. Mean arterial blood pressure (MABP) and heart rate (HR) were recorded continuously under baseline conditions and during infusions into the lateral cerebral ventricle (LCV) of the experimental animals. In control series LCV infusion of vehicle (Krebs-Henseleit bicarbonate-buffer) did not cause significant changes in MABP or HR. LCV infusion of H2S donor (NaHS) at the rate of 400 nM/h resulted in an increase in MABP, whereas infusions at the rate of 100 nM/h and 200 nM/h failed to change MABP. On the other hand LCV infusion of H2S donor at the rate of 200 nM/h caused a significant increase in HR while infusion at the rate of 400 nM/h produced an increase in HR, which was smaller than this observed during infusion at the rate of 200 nM/h. H2S donor administered at the rate of 100 nM/h failed to affect HR. In conclusion, the present study demonstrates that exogenous hydrogen sulfide changes hemodynamic parameters by centrally mediated mechanisms. The hemodynamic effect seems to be dependent on H2S concentration in cerebrospinal fluid. It appears that the hypertensive response may occur at a concentration, which does not exceed twice the physiological level.

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Enhanced pressor response to centrally administered vasopressin in WKY rats on high sodium diet

Centrally applied vasopressin prevents posthemorrhagic hypotension in WKY rats

Exogenous hydrogen sulfide produces hemodynamic effects by triggering central neuroregulatory mechanisms