Ganz M B, Perfetto M C, Boron W F
Renal Division, West Haven Veterans Administration Medical Center, Connecticut 06516.
Am J Physiol. 1990 Aug;259(2 Pt 2):F269-78. doi: 10.1152/ajprenal.1990.259.2.F269.
We investigated effects of various agents on proliferation, intracellular pH (pHi), and intracellular calcium [( Ca2+]i) of rat mesangial cells (MCs) in early passages (2-5). Serum-starved MCs incubated in HCO3- were exposed to one of the following: fetal calf serum (FCS), serotonin, angiotensin II (ANG II), arginine vasopressin (AVP), bombesin (Bom), bradykinin (BK), epidermal growth factor (EGF), epinephrine (Epi), interleukin 1 (IL-1), norepinephrine (NE), neuropeptide Y, oxytocin, substance P (SP), platelet-derived growth factor, or 12-O-tetradecanoylphorbol-13-acetate (TPA). We assessed DNA synthesis from [3H]thymidine uptake during exposure to test agent. All agents except ANG II, NE, Bom, and SP were mitogenic. When MCs were incubated in a HCO3(-) -free N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid-buffered medium, maximal mitogenic responses to FCS, AVP, and EGF were 41, 44, and 55% (P less than 0.01) lower, respectively, than those in presence of HCO3-. In absence of HCO3-, agents other than BK and IL-1 produced a biphasic pHi response characterized by a transient acidification followed by a prolonged alkalinization that was both Na(+)-dependent and amiloride-sensitive. In presence of HCO3-, agents produced only a small and gradual acidification, except for IL-1 and Epi. Addition of all agonists except IL-1, EGF, and TPA produced significant transient increases in [Ca2+]i, the magnitudes of which were similar in HCO3- and non-HCO3- buffers. These results demonstrate that, in presence of HCO3-, agents (i.e., NE and ANG II) can produce typical [Ca2+]i transients and still not cause MC proliferation. Conversely, an agent may cause proliferation without eliciting a short-term change in either [Ca2+]i or pHi (i.e., IL-1), a change in [Ca2+]i but not pHi (i.e., Epi), or a change in pHi but not [Ca2+]i (i.e., TPA). Thus, at least for MCs, proliferation in HCO3- can be dissociated from early agonist-induced changes in pHi and [Ca2+]i.
我们研究了多种因子对早期传代（2 - 5代）大鼠系膜细胞（MCs）增殖、细胞内pH值（pHi）和细胞内钙浓度[Ca2+]i的影响。将血清饥饿的MCs置于含HCO3-的培养基中，然后分别暴露于以下因子之一：胎牛血清（FCS）、5-羟色胺、血管紧张素II（ANG II）、精氨酸加压素（AVP）、蛙皮素（Bom）、缓激肽（BK）、表皮生长因子（EGF）、肾上腺素（Epi）、白细胞介素1（IL-1）、去甲肾上腺素（NE）、神经肽Y、催产素、P物质（SP）、血小板衍生生长因子或12-O-十四烷酰佛波醇-13-乙酸酯（TPA）。我们通过检测暴露于测试因子期间[3H]胸腺嘧啶核苷摄取来评估DNA合成。除ANG II、NE、Bom和SP外，所有因子均具有促有丝分裂作用。当MCs在不含HCO3-的N-2-羟乙基哌嗪-N'-2-乙烷磺酸缓冲培养基中培养时，对FCS、AVP和EGF的最大促有丝分裂反应分别比在含HCO3-时低41%、44%和55%（P < 0.01）。在不含HCO3-的情况下，除BK和IL-1外，其他因子均产生双相pHi反应，其特征为先短暂酸化，随后长时间碱化，且该过程依赖Na+并对氨氯吡脒敏感。在含HCO3-的情况下，除IL-1和Epi外，其他因子仅产生轻微且逐渐的酸化。除IL-1、EGF和TPA外，添加所有激动剂均导致[Ca2+]i显著短暂升高，在含HCO3-和不含HCO3-的缓冲液中升高幅度相似。这些结果表明，在含HCO3-的情况下，一些因子（如NE和ANG II）可产生典型的[Ca2+]i瞬变，但不会引起MCs增殖。相反，一种因子可能导致增殖，而不引起[Ca2+]i或pHi的短期变化（如IL-1）、仅引起[Ca2+]i变化而不引起pHi变化（如Epi）或仅引起pHi变化而不引起[Ca2+]i变化（如TPA）。因此，至少对于MCs来说，在含HCO3-环境中的增殖可与激动剂早期诱导的pHi和[Ca2+]i变化相分离。
