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Renal lymphatic obstruction in diabetic rats induces systemic hypotension
1Department of Nephrology, Walter Reed Army Institute of Research, Washington, DC.
Abstract:
We obstructed renal lymph drainage from a single kidney in diabetic rats who had received 65 mg/kg streptozotocin 6 months prior to the study. Lymphatic obstruction led to a progressive fall in systematic blood pressure from a mean arterial pressure of 101 +/- 5 (SEM) mm Hg (n = 7) to 62 +/- 4 mm Hg (n = 5) (p < .02) after 1.5 h. No change was seen in a sham-operated animal. Despite the decline in systemic blood pressure there was no significant change in the GFR of either kidney. Sodium excretion increased significantly in the experimental kidney. There was no change in the urinary excretion of cyclic GMP from either kidney, and plasma levels of atrial natriuretic peptide (ANP) did not change (55 +/- 21 pg/mL pre- to 64 +/- 18 postobstruction). The results are consistent with a systemic vasodilatation after lymphatic obstruction. The mechanism of this response is still under investigation, but apparently it does not involve ANP.
Insights
Obstructing renal lymph drainage in diabetic rats caused a significant drop in blood pressure. This response, possibly systemic vasodilation, did not involve atrial natriuretic peptide (ANP).
Area of Science:
- Nephrology
- Cardiovascular Physiology
- Diabetology
Background:
- Diabetic nephropathy is a major complication of diabetes mellitus.
- Renal lymphatic system's role in kidney function and blood pressure regulation is not fully understood.
- Previous research suggests a link between lymphatic system and systemic hemodynamics.
Purpose of the Study:
- To investigate the effect of renal lymphatic obstruction on systemic blood pressure and kidney function in a rat model of diabetes.
- To explore the potential involvement of atrial natriuretic peptide (ANP) in the observed hemodynamic changes.
Main Methods:
- Induction of diabetes in rats using streptozotocin.
- Surgical obstruction of lymphatic drainage from a single kidney.
- Monitoring of mean arterial pressure, glomerular filtration rate (GFR), and sodium excretion.
- Measurement of urinary cyclic guanosine monophosphate (cGMP) and plasma ANP levels.
Main Results:
- Renal lymphatic obstruction led to a significant decrease in mean arterial pressure (MAP) from 101 mmHg to 62 mmHg within 1.5 hours.
- No significant changes in GFR were observed in either kidney despite the drop in MAP.
- Sodium excretion increased significantly in the obstructed kidney, while urinary cGMP and plasma ANP levels remained unchanged.
Conclusions:
- Renal lymphatic obstruction induces systemic vasodilation in diabetic rats.
- The observed vasodilation does not appear to be mediated by atrial natriuretic peptide (ANP).
- The precise mechanism underlying this systemic hemodynamic response warrants further investigation.