Guanabenz-induced inhibition of aldosterone secretion from isolated rat adrenal glomerulosa cells

Six Decades of History of Hypertension Research at the University of Toledo: Highlighting Pioneering Contributions in Biochemistry, Genetics, and Host-Microbiota Interactions

PURPOSE OF REVIEW

The study aims to capture the history and lineage of hypertension researchers from the University of Toledo in Ohio and showcase their collective scientific contributions dating from their initial discoveries of the physiology of adrenal and renal systems and genetics regulating blood pressure (BP) to its more contemporary contributions including microbiota and metabolomic links to BP regulation.

RECENT FINDINGS

The University of Toledo College of Medicine and Life Sciences (UTCOMLS), previously known as the Medical College of Ohio, has contributed significantly to our understanding of the etiology of hypertension. Two of the scientists, Patrick Mulrow and John Rapp from UTCOMLS, have been recognized with the highest honor, the Excellence in Hypertension award from the American Heart Association for their pioneering work on the physiology and genetics of hypertension, respectively. More recently, Bina Joe has continued their legacy in the basic sciences by uncovering previously unknown novel links between microbiota and metabolites to the etiology of hypertension, work that has been recognized by the American Heart Association with multiple awards. On the clinical research front, Christopher Cooper and colleagues lead the CORAL trials and contributed importantly to the investigations on renal artery stenosis treatment paradigms. Hypertension research at this institution has not only provided these pioneering insights, but also grown careers of scientists as leaders in academia as University Presidents and Deans of Medical Schools. Through the last decade, the university has expanded its commitment to Hypertension research as evident through the development of the Center for Hypertension and Precision Medicine led by Bina Joe as its founding Director. Hypertension being the top risk factor for cardiovascular diseases, which is the leading cause of human mortality, is an important area of research in multiple international universities. The UTCOMLS is one such university which, for the last 6 decades, has made significant contributions to our current understanding of hypertension. This review is a synthesis of this rich history. Additionally, it also serves as a collection of audio archives by more recent faculty who are also prominent leaders in the field of hypertension research, including John Rapp, Bina Joe, and Christopher Cooper, which are cataloged at Interviews .

LC-MS/MS determination of guanabenz E/Z isomers and its application to in vitro and in vivo DMPK profiling studies

Endoplasmic reticulum (ER) stress underlies a variety of disorders involving inflammation, such as diabetes, neurodegenerative diseases. Guanabenz acetate (Wytensin®, GA), a clinically approved antihypertensive drug, efficiently counteracts ER stress. The entirety of clinically used GA is the E-isomer, while the Z-isomer is known to lack significant hypotensive properties. We recently discovered that the Z-isomer retains anti-ER stress activity. Coupled with its lack of sedative effects, (Z)-GA is well positioned as a potential therapeutic for a host of ER stress-related disorders. We set forth to characterize the metabolism and pharmacokinetics (DMPK) of (Z)-GA in vitro and in vivo. Toward this end, a reliable and sensitive LC-MS/MS method for simultaneous determination of the (E)- and (Z)-guanabenz was developed. Chromatographic separation of the isomers was achieved on a C18 reverse phase column with a gradient elution. Tandem mass spectrometric detection was conducted using an AB Sciex 5500 QTrap mass spectrometer with positive electrospray ionization. Full validation of the method was performed in mouse plasma with a simple and low plasma volume protein precipitation procedure. The method demonstrated good linearity, reproducibility, and accuracy over a range of 0.5-1000 nM with minimal matrix effect and excellent extraction efficiency. In addition, the developed method was successfully applied to DMPK studies of the GA isomers in vitro and in vivo. Results of these studies revealed for the first time that the DMPK profile of (Z)-guanabenz is distinct from that of (E)-guanabenz, with higher apparent volume of distribution (V_d) and clearance, presumably due to lower plasma protein binding.

Locally generated angiotensin II in the adrenal gland regulates basal, corticotropin-, and potassium-stimulated aldosterone secretion

The zona glomerulosa cells of the adrenal gland have an intrinsic renin-angiotensin system that appears to modulate the aldosterone response to potassium and corticotropin. The actions of circulating angiotensin II (Ang II) are mediated by the activation of the Ang II type 1 (AT1) receptor on the adrenal cortex. In this study we examined the effects of the AT1 receptor antagonist DuP 753 and other antagonists on aldosterone secretion in cultured bovine zona glomerulosa cells. Zona glomerulosa cells were cultured in PFMR-4 medium containing 10% fetal calf serum for 72 hours, and the medium was replaced with serum-free medium for the next 24-hour experimental period. DuP 753 (10 mumol/L) inhibited basal aldosterone secretion (from 88.6 +/- 7.1 to 54.8 +/- 9.6 pg/10(6) cells per hour; 38% inhibition). EXP 3174, an active metabolite of DuP 753, also inhibited aldosterone dose dependently (from 88.6 +/- 7.1 to 55.9 +/- 8.4 at 1 mumol/L and 88.6 +/- 7.1 to 21.7 +/- 3.3 at 100 mumol/L; 37% and 75% inhibition, respectively). Another and more potent AT1 receptor antagonist, L158,809, showed significant inhibition at 100 nmol/L, and at 10 mumol/L it inhibited basal aldosterone secretion (from 144.7 +/- 18.2 to 83.4 +/- 17.1 pg/10(6) cells per hour; 42% inhibition). DuP 753 inhibited Ang II (100 nmol/L)-stimulated aldosterone production in a dose-dependent fashion, with a 30% reduction at 100 nmol/L and complete inhibition at 100 mumol/L. DuP 753 also inhibited potassium (12 nmol/L) and corticotropin (1 nmol/L) stimulation of aldosterone in a dose-dependent fashion.(ABSTRACT TRUNCATED AT 250 WORDS)