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Properties of Dissociated Paraventricular Nucleus (PVN) Neurons following Hindlimb Unloading (HU) in Rats
Author(s) -
KuehlKovarik M Cathleen,
Kline David D,
Hasser Eileen M
Publication year - 2009
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.23.1_supplement.792.5
Subject(s) - microinjection , baroreflex , medicine , chemistry , endocrinology , spinal cord , reflex , brainstem , hindlimb , neuroscience , biology , heart rate , blood pressure
Cardiovascular deconditioning (CVD) alters autonomic regulation, including arterial and cardiopulmonary baroreflex function. Cardiopulmonary reflex sympathoinhibition is enhanced in HU rats, an animal model for CVD and the PVN may be involved. We hypothesized that HU alters intrinsic properties of PVN neurons involved in autonomic control. Male rats underwent microinjection of fluorescent, retrograde beads into the spinal cord, allowed to recover and subjected to HU (n = 3) or control (C, n = 3) for 14 days. Rats were euthanized and PVN cells acutely dissociated. Whole cell patch clamp recordings were made on labeled spinally projecting neurons. Input resistance and capacitance were similar in cells from C and HU. Spike frequency adaptation (SFA) was significantly greater in neurons from HU rats compared to C (+35 pA step; 1.8±0.8 vs 5.8±0.9 spikes, p=0.01). Delayed excitation was similar in neurons from both groups. Ionic mechanisms for greater SFA in HU rats were evaluated. In a small number of cells, outward currents were similar between groups. However, in cells (n=5) from HU rats, inward currents appeared to be blunted compared to C (n=6) (@ ‐20 mV: HU = ‐1428±371 pA; C = ‐4918±1142 pA; p = 0.03). Preliminary data are consistent with the concept that, in HU rats, spinally projecting PVN neurons display properties that reduce their excitability. These changes could contribute to altered autonomic regulation in CVD. HL55306