Mahassini, "Juxtaglomerular cell
tumor: A distinct mesenchymal tumor of kidney," Journal of Clinical Imaging Science, vol.
Schweda et al., "Increased renin production in mice with deletion of peroxisome proliferator-activated receptor-y in juxtaglomerular cells
," Hypertension, vol.
In recent years it has been noticed that the first step in the RAAS cascade, the release of renin from juxtaglomerular cells
in response to an activation of the sympathetic nervous system, is far more than the release of an aspartyl protease required for converting angiotensinogen into angiotensin I.
Normally, NE released by the sympathetic nerve endings causes salt and water reabsorption through a direct action on the renal tubules, reduction in RBF via activation of postsynaptic [[alpha].sub.1]-adrenergic receptors and to a lesser extent postsynaptic [[alpha].sub.2]-adrenergic receptors on the renal vasculature, and/ or a direct action on [[beta].sub.1]-adrenergic receptors on the juxtaglomerular cells
which consequently augments renin secretion and Ang II formation (3,4,20,22,23).
These results suggest that the beneficial effects of Panamanian plant extracts on the cardiovascular system do not involve effects on the [beta]1 receptors which are located in the heart and control its contractile force and rate, or the juxtaglomerular cells
of the kidney which control the release of renin which activates the renin-angiotensin system.
The enzyme renin ([M.sub.r] ~40 000) is released in an active form from the renal juxtaglomerular cells
in response to physiologic factors, including sodium depletion, decreased blood volume and blood pressure, and [beta]-adrenergic stimulation (1).
Fluctuations in the degree of RSNA modulate renin secretion from juxtaglomerular cells
and sodium reabsorption from renal tubular cells (1,5,9).
Renin is normally released from the juxtaglomerular cells
in response to stimuli such as decreased blood flow to the kidney or increased sympathetic tone.