Voltage-gated divalent currents in descending vasa recta pericytes

Area of Science:

• Nephrology
• Cardiovascular Physiology
• Molecular Biology

Background:

• Juxtamedullary glomerular arterioles play a key role in kidney function.
• Voltage-gated calcium channel (Ca(V)) subtypes are implicated in regulating renal vascular tone.
• Pericytes in descending vasa recta (DVR) are critical for controlling blood flow.

Purpose of the Study:

• To investigate the specific types of voltage-gated calcium channels present in DVR pericytes.
• To characterize the electrophysiological properties of Ca(V) currents in these cells.
• To determine the role of these channels in regulating DVR vasoconstriction.

Main Methods:

• Whole-cell patch-clamp electrophysiology was used to record Ca(V) currents in DVR pericytes.
• Specific Ca(V) channel agonists (FPL64176) and antagonists (nifedipine, Ni(2+), diltiazem, calciseptine, mibefradil, ω-agatoxin IVA) were employed.
• Currents were analyzed for activation/inactivation kinetics, ion selectivity, and voltage dependence.
• The effect of channel blockers on angiotensin II-induced vasoconstriction was assessed.

Main Results:

• FPL64176 stimulated inward Ca(2+) and Ba(2+) currents consistent with L-type Ca(V) channels.
• These currents exhibited slow inactivation, were blocked by nifedipine and Ni(2+), and conducted Ba(2+) more effectively than Ca(2+).
• Basal currents in Ba(2+) were also blocked by nifedipine and diltiazem, confirming L-type channel activity.
• Specific blockers like calciseptine and mibefradil showed limited effects on basal currents and ANG II-induced vasoconstriction.

Conclusions:

• Descending vasa recta pericytes predominantly express L-type voltage-gated calcium channels.
• These L-type channels are responsible for the majority of voltage-gated divalent currents in DVR pericytes.
• The findings provide insight into the mechanisms of renal vascular regulation by DVR pericytes.