Research Interests

Integrative systems physiology

Regulation of fluid balance and blood pressure

Control of renal renin secretion and renal sodium excretion 

Research information

The research area is the control systems regulating fluid balance and arterial blood pressure under normal and pathological conditions. Research focus is the hormonal control of fluid balance, especially the regulation of the secretion of renin thorugh interaction between brain, heart, and kidney functions. Experimental models have included awake, freely moving rats, trained dogs, human volunteers, and selected patients with uncomplicated hypertension. It has been shown that the physiological control of renin secretion takes place in the absence of (i) changes renal arterial pressure and renal synpathetic nerve activity, and (ii) measurable changes in GFR. Renin secretion, therefore, is regulated by neurohomural control af proximal tubular reabsorption and/or by minute changes in GFR. We have shown in hypertensive patients that the natriuresis elicited by volume expansion is not preceded by elevations in regional, renal blood flows despite a minor increase in arterial blood pressure. In this perspective, sodium excretion in response to elevation in arterial pressure ('pressure natriuresis') seems to be a back-up mechanism activated only under certain pathophysiological conditions. 

Recent publications:

2021

Al-Mashhadi RH, Al-Mashhadi AL, Nasr ZP, Mortensen MB, Lewis EA, Camafeita E, Ravlo K, Al-Mashhadi Z, Kjær DW, Palmfeldt J, Bie P, Jensen JM, Nørgaard BL, Falk E, Vázquez J, Bentzon JF. Local Pressure Drives Low-Density Lipoprotein Accumulation and Coronary Atherosclerosis in Hypertensive Minipigs. J Am Coll Cardiol 2021 77: 575-589, 2021. doi: 10.1016/j.jacc.2020.11.059

Bie P: Strong ion difference: Inconsistencies lining up. Acta Physiol (Oxf): 232(2):e13616, 2021. (letter) doi: 10.1111/apha.13616.

Bie P: Strong ion difference: Questionable stewardship. Acta Physiol (Oxf) Apr 26;e13667, 2021. doi: 10.1111/apha.13667. Online ahead of print.

2019

Assersen KB, Høilund‐Carlsen PF, Olsen MH, Greve SV, Gam-Hadberg HC, Braad P-E, Damkjær M and Bie P. The exaggerated natriuresis of essential   hypertension occurs independently of changes in renal medullary blood flow. Acta Physiol. 226: e13266, 2019. DOI 10.1111/apha.13266

2018

Bie P: Natriuretic peptides and normal body fluid regulation. Compr Physiol 8: 1211-1249, 2018.

Bie P: Mechanism of Sodium Balance: Total body sodium, surrogate variables and renal sodium balance.  Am J Physiol Regul Integr Comp Physiol 315: R945-R962, 2018. doi 10.1152/ajpregu.00363.2017