Abstract: TH-OR054

In Two-Kidney One-Clip Hypertensive Sheep Cardiac and Contralateral Renal Sympathetic Nerve Activity Are Differentially Controlled

Session Information

Category: Hypertension

  • 1101 Hypertension: Basic and Experimental - Neural and Inflammatory Mechanisms

Authors

  • Tromp, Tycho R, University Medical Center Utrecht, Utrecht, Netherlands
  • Joles, Jaap A., University Medical Center Utrecht, Utrecht, Netherlands
  • Ramchandra, Rohit, The University of Aucklad, Auckland, New Zealand
Background

Hypertension is often initiated and maintained by elevated sympathetic tone. We investigated changes in directly recorded sympathetic nerve activity (SNA) to the heart and nonclipped kidney in two-kidney one-clip (2K-1C) hypertensive sheep.

Methods

Adult ewes either underwent unilateral renal artery clipping (n=12) or sham surgery (n=15). Two weeks later, the carotid artery was cannulated and electrodes were placed in the (nonclipped) renal and/or cardiac nerve. Blood pressure (BP), heart rate (HR) and baseline and baroreflex control of SNA were recorded in the conscious sheep one week later.

Results

Unilateral renal artery clipping induced hypertension (systolic blood pressure 130±3 vs 111±4 mmHg in shams, p<0.001) after 21±5 days, and shifted the heart rate baroreflex curve rightwards (BP50 120±13 vs 104±16 mmHg, p<0.01). HR was unchanged. The renal SNA (RSNA) baroreflex curve was also shifted rightwards (BP50 93±3 vs 78±2, p<0.01) and showed increased gain (p<0.05). In the hypertensive group, cardiac SNA (CSNA) burst incidence (bursts/100 beats) was increased (39±14 vs 25±9 in normotensives, p<0.05), whereas RSNA burst incidence was decreased (69±20 vs 93±8 in normotensives, p<0.01).

Conclusion

In this ovine model of 2K-1C renovascular hypertension we show that cardiac and contraleteral renal sympathetic nerve activity were differentially controlled three weeks after clipping: baseline CSNA was increased whilst RNSA to the nonclipped kidney was decreased. We speculate that the observed contralateral RSNA decrease is a homeostatic response to increased blood pressure and the sodium avid state of the clipped kidney.

Differential control of contralateral renal and cardiac sympathetic nerve activity (SNA). Baseline contralateral renal SNA was decreased whereas cardiac SNA was increased (A). Baroreflex control of contralateral renal (B) and cardiac SNA (C) was differentially regulated.

Funding

  • Private Foundation Support