Julian H. Lombard, PhD

Professor; Physiology Course Director

Locations

Physiology

Contact Information

Biography

Education

PhD, Physiology, Medical College of Wisconsin, 1975
MS, Zoology, Arizona State University, 1971
BA, Biological Sciences, University of Texas, El Paso, 1969

Research Interests

Cardiovascular Physiology | Molecular and Cellular Physiology

Current research in this laboratory utilizes television microscopy, optical Doppler velocity measurements, oxygen microelectrodes, electrophysiological techniques and molecular biology to investigate the mechanisms by which changes in oxygen availability regulate active tone in microvessels and small resistance arteries and how elevated dietary salt intake affects vascular control in salt-sensitive hypertension and in normotensive animals that are not salt-sensitive. We previously demonstrated that resistance vessels of hypertensive animals exhibit an enhanced constriction in response to elevated PO2, and a reduced dilation in response to decreased PO2. We have also found that consumption of a high salt diet leads to a dramatic reduction in the ability of blood vessels to relax and increase blood flow to critical organs, and that this occurs without an increase in blood pressure.

A major goal of our work is to determine the mechanisms of the altered response of arterioles and small resistance arteries to changes in oxygen availability in hypertension. Another major goal of our laboratory is to identify the mechanisms by which high salt diet leads to impaired vascular function, even in the absence of an elevation in blood pressure. We are also investigating the role of circulating angiotensin II (ANG II) in maintaining normal vascular relaxation mechanisms using novel genetic rat strains [salt sensitive (SS) rats and consomic SS.13 BN rats) that differ in their ability to regulate their renin-angiotensin system and maintain normal circulating ANG II levels. In those studies, restoration of normal regulation of ANG II by substitution of the Brown Norway chromosome 13 (in SS.13 BN consomic rats) restores normal vascular relaxation mechanisms that are lost in SS rats, even when they are fed a low salt diet.

Mechanisms of Mas1 Receptor-Mediated Signaling in the Vascular Endothelium.

(Hoffmann BR, Stodola TJ, Wagner JR, Didier DN, Exner EC, Lombard JH, Greene AS.) Arterioscler Thromb Vasc Biol. 2017 Mar;37(3):433-445.
Role of vascular reactive oxygen species in regulating cytochrome P450-4A enzyme expression in Dahl salt-sensitive rats.

(Lukaszewicz KM, Paudyal MP, Falck JR, Lombard JH.) Microcirculation. 2016 10;23(7):540-548.
Angiotensin-(1-7) Selectively Induces Relaxation and Modulates Endothelium-Dependent Dilation in Mesenteric Arteries of Salt-Fed Rats.

(Raffai G, Lombard JH.) J Vasc Res. 2016;53(1-2):105-118.
Salt, Angiotensin II, Superoxide, and Endothelial Function.

(Boegehold MA, Drenjancevic I, Lombard JH.) Compr Physiol. 2015 Dec 15;6(1):215-54.
Increased peripheral vascular disease risk progressively constrains perfusion adaptability in the skeletal muscle microcirculation.

(Frisbee JC, Butcher JT, Frisbee SJ, Olfert IM, Chantler PD, Tabone LE, d'Audiffret AC, Shrader CD, Goodwill AG, Stapleton PA, Brooks SD, Brock RW, Lombard JH.) Am J Physiol Heart Circ Physiol. 2016 Feb 15;310(4):H488-504.
The NRF2 knockout rat: a new animal model to study endothelial dysfunction, oxidant stress, and microvascular rarefaction.

(Priestley JR, Kautenburg KE, Casati MC, Endres BT, Geurts AM, Lombard JH.) Am J Physiol Heart Circ Physiol. 2016 Feb 15;310(4):H478-87.
The role of cyclo-oxygenase-1 in high-salt diet-induced microvascular dysfunction in humans.

(Cavka A, Cosic A, Jukic I, Jelakovic B, Lombard JH, Phillips SA, Seric V, Mihaljevic I, Drenjancevic I.) J Physiol. 2015 Dec 15;593(24):5313-24.
Enhancement of resting-state fcMRI networks by prior sensory stimulation.

(Li C, Li Z, Ward BD, Dwinell MR, Lombard JH, Hudetz AG, Pawela CP.) Brain Connect. 2014 Nov;4(9):760-8.
Vascular dysfunction precedes hypertension associated with a blood pressure locus on rat chromosome 12.

(Prisco SZ, Priestley JR, Weinberg BD, Prisco AR, Hoffman MJ, Jacob HJ, Flister MJ, Lombard JH, Lazar J.) Am J Physiol Heart Circ Physiol. 2014 Oct 15;307(8):H1103-10.
Mutation of Plekha7 attenuates salt-sensitive hypertension in the rat.

(Endres BT, Priestley JR, Palygin O, Flister MJ, Hoffman MJ, Weinberg BD, Grzybowski M, Lombard JH, Staruschenko A, Moreno C, Jacob HJ, Geurts AM.) Proc Natl Acad Sci U S A. 2014 Sep 02;111(35):12817-22.
Response to Does angiotensin-dependent superoxide production help to prevent salt-induced endothelial dysfunction in 2 kidney-1 clip hypertensive rats?.

(Beyer AM, Fredrich K, Lombard JH.) Am J Hypertens. 2014 Apr;27(4):640.
Amelioration of salt-induced vascular dysfunction in mesenteric arteries of Dahl salt-sensitive rats by missense mutation of extracellular superoxide dismutase.

(Beyer AM, Raffai G, Weinberg BD, Fredrich K, Rodgers MS, Geurts AM, Jacob HJ, Dwinell MR, Lombard JH.) Am J Physiol Heart Circ Physiol. 2014 Feb;306(3):H339-47.

Julian H. Lombard, PhD