Myocardial water handling and the role of aquaporins

Cardiac surgery is performed in approximately 770,000 adults and 30,000 children in the United States of America annually. In this review we outline the mechanistic links between post-operative myocardial stunning and the development of myocardial edema. These interrelated processes cause a decline in myocardial performance that account for significant morbidity and mortality after cardiac surgery. Factors leading to myocardial edema include hemodilution, ischemia and reperfusion as well as osmotic gradients arising from pathological change. Several members of the aquaporin family of water transport proteins have been described in the myocardium although their role in the pathogenesis and resolution of cardiac edema is not established. This review examines evidence for the involvement of aquaporins in myocardial water handling during normal and pathological conditions.     

Birth of water channel proteins-the aquaporins

If we compare aquaporin (as a proteic pathway for water permeation across biological membranes) with a child we can say that he had a very long gestation period. His possible existence was predicted for a long time (Overton in 1985, Stein and Danielli in 1956), some of his features (transport of water and its reversible inhibition) were assigned by Macey and Farmer in 1970, however this child was first detected by Benga and coworkers in 1986. We clearly demonstrated for the first time the presence and location of a water channel at the human RBC membrane among the polypeptides migrating in the region having 35-60 kDa on the electrophoretogram of RBC membranes, labeled with 203Hg-PCMBS in the conditions of specific inhibition of water diffusion; I suggested that a minor membrane protein that binds PCMBS is involved in water transport and also indicated the way in which the specific protein could be further characterized: by purification and reconstitution in liposomes. Our landmark papers in 1986 can be compared with the first detection of a child "in utero" by ultrasonography, since we discovered one of the essential components of the "aquaporin child" (a molecular weight of 35-60 kDa for the glycosylated component); we have also indicated the way to recognize him after birth (among other children of his group!): placing the isolated children in a certain environment and asking them to perform the same task (one should read: reconstitution studies in liposomes and measurement of water permeability), like aligning athletes for a running test. This was the only certain way to know that the child is really the fastest runner and not just one that is helping (by various means) another child to be fastest runner. A "new child" was observed in 1988 by Agre and coworkers, who identified a novel integral membrane protein in human RBCs having a non-glycosylated component of 28 kDa and a glycosylated component migrating as a diffuse band of 35-60 kDa; they suggested that the new protein (nick-named CHIP28 in 1991) may play a role in linkage of the membrane skeleton to the lipid bilayer. In 1992 Agre and coworkers suggested that CHIP28 is a functional unit of membrane water channels; by reconstitution in liposomes it was demonstrated that CHIP28 is a water channel itself rather than a water channel regulator. In other words the child we first detected was recognized as having the predicted qualities only in 1992. In 1993 CHIP28 was renamed aquaporin 1. Looking in retrospect, asking the crucial question, when was the first water channel protein, aquaporin 1, discovered, a fair and clear cut answer would be: the first water channel protein, now called aquaporin 1, was identified or "seen" in situ in the human RBC membrane by Benga and coworkers in 1986. It was again "seen" when it was by chance purified by Agre and coworkers in 1988 and was again identified when its main feature, the water transport property was found by Agre and coworkers in 1992. If a comparison with the discovery of The New World of America is made, the first man who has "seen" a part, very small indeed, of The New Land was Columbus; later, others, including Amerigo Vespucci (from whom the name derived), have better "seen" a larger part of the new Continent and in the subsequent years many explorers discovered the complexity of the Americas!     

左旋精氨酸在冠脉搭桥术中心肌保护效果研究

目的：通过在心脏停搏液中添加适量左旋精氨酸来观察其在冠脉搭桥术中心肌保护效果。方法：选择2008年1月~2010年1月在我院行冠状动脉旁路移植术患者20例,随机分为2组,每组10例,对照组：常规心肌保护液组,不添加左旋精氨酸。实验组,心肌保护液中加入7．5gm左旋精氨酸。测患者术前（T1）、术后6小时（T2）、术后12小时（T3）、术后24小时（T4）、术后48小时（T5）血浆中TNF-α、IL-6、IL-8及cTnI含量。记录临床观察指标。结果：两组血浆TNF-α、IL．6、IL-8、cTnI浓度术前无统计学意义（P〉0．05）,术后各时点TNF-α、1L-6、IL．8、cTnI浓度显著升高且实验组均低于对照组（P〈0．05）。临床观察指标除血管活性药物应用情况实验组优于对照组（P〈0．05）外无明显差异。结论：在心脏停搏液中加入L-精氨酸,可有效保护缺血心肌,减轻心肌再灌注损伤程度。     

同期施行冠状动脉搭桥和心脏瓣膜手术的体外循环

目的总结和分析同期施行冠状动脉搭桥和心脏瓣膜手术的体外循环方法。方法125例患者分为3组:M组(冠脉病变及二尖瓣病变)75例,A组(冠脉病变及主动脉瓣病变)34例,D组(冠脉病变及二尖瓣和主动脉瓣病变)16例。心肌保护采用4:1冷含血停搏液,应用单纯顺灌、顺灌逆灌结合、顺灌桥灌结合、顺逆灌和桥灌结合技术。结果术中转流平稳,血流动力学稳定,监测指标均在正常范围,无手术死亡。结论同期施行冠状动脉搭桥和心脏瓣膜手术,术中良好的心肌保护方法和合理的体外循环灌注是保证手术顺利成功的重要因素。     

左旋精氨酸在冠脉搭桥术中心肌保护效果研究

目的:通过在心脏停搏液中添加适量左旋精氨酸来观察其在冠脉搭桥术中心肌保护效果。方法:选择2008年1月～2010年1月在我院行冠状动脉旁路移植术患者20例,随机分为2组,每组10例,对照组:常规心肌保护液组,不添加左旋精氨酸。实验组,心肌保护液中加入7.5g/L左旋精氨酸。测患者术前(T1)、术后6小时(T2)、术后12小时(T3)、术后24小时(T4)、术后48小时(T5)血浆中TNF-α、IL-6、IL-8及cTn I含量。记录临床观察指标。结果:两组血浆TNF-α、IL-6、IL-8、cTn I浓度术前无统计学意义(P>0.05),术后各时点TNF-α、IL-6、IL-8、cTn I浓度显著升高且实验组均低于对照组(P<0.05)。临床观察指标除血管活性药物应用情况实验组优于对照组(P<0.05)外无明显差异。结论:在心脏停搏液中加入L-精氨酸,可有效保护缺血心肌,减轻心肌再灌注损伤程度。     

The structural basis of water permeation and proton exclusion in aquaporins (Review)

Aquaporins (AQPs) represent a ubiquitous class of integral membrane proteins that play critical roles in cellular osmoregulations in microbes, plants and mammals. AQPs primarily function as water-conducting channels, whereas members of a sub-class of AQPs, termed aquaglyceroporins, are permeable to small neutral solutes such as glycerol. While AQPs facilitate transmembrane permeation of water and/or small neutral solutes, they preclude the conduction of protons. Consequently, openings of AQP channels allow rapid water diffusion down an osmotic gradient without dissipating electrochemical potentials. Molecular structures of AQPs portray unique features that define the two central functions of AQP channels: effective water permeation and strict proton exclusion. This review describes AQP structures known to date and discusses the mechanisms underlying water permeation, proton exclusion and water permeability regulation.     

Effect of dietary conjugated linoleic acid isomers on water and glycerol permeability of kidney membranes

Conjugated linoleic acid (CLA) refers to a group of positional and geometrical isomers of linoleic acid in which the double bonds are conjugated. Dietary CLA has been associated with various health benefits although details of its molecular mode of action remain elusive. The effect of CLA supplemented to palm oil-based diets in Wistar rats, as a mixture of both or isolated c9,t11 and t10,c12 isomers, was examined on water and glycerol membrane permeability of kidney proximal tubule. Although water permeability was unaltered, an increase in glycerol permeability was obtained for the group supplemented with CLA mixture, even though the activation energy for glycerol permeation remained high. This effect was correlated with an increased CLA isomeric membrane incorporation for the same dietary group. These results suggest that diet supplementation with CLA mixture, in contrast to its individual isomers, may enhance membrane fluidity subsequently raising kidney glycerol reabsorption.     

Cardiac Restricted Overexpression of Membrane Type-1 Matrix Metalloproteinase Causes Adverse Myocardial Remodeling following Myocardial Infarction

The membrane type-1 matrix metalloproteinase (MT1-MMP) is a unique member of the MMP family, but induction patterns and consequences of MT1-MMP overexpression (MT1-MMPexp), in a left ventricular (LV) remodeling process such as myocardial infarction (MI), have not been explored. MT1-MMP promoter activity (murine luciferase reporter) increased 20-fold at 3 days and 50-fold at 14 days post-MI. MI was then induced in mice with cardiac restricted MT1-MMPexp (n = 58) and wild type (WT, n = 60). Post-MI survival was reduced (67% versus 46%, p < 0.05), and LV ejection fraction was lower in the post-MI MT1-MMPexp mice compared with WT (41 ± 2 versus 32 ± 2%,p < 0.05). In the post-MI MT1-MMPexp mice, LV myocardial MMP activity, as assessed by radiotracer uptake, and MT1-MMP-specific proteolytic activity using a specific fluorogenic assay were both increased by 2-fold. LV collagen content was increased by nearly 2-fold in the post-MI MT1-MMPexp compared with WT. Using a validated fluorogenic construct, it was discovered that MT1-MMP proteolytically processed the pro-fibrotic molecule, latency-associated transforming growth factor-1 binding protein (LTBP-1), and MT1-MMP-specific LTBP-1 proteolytic activity was increased by 4-fold in the post-MI MT1-MMPexp group. Early and persistent MT1-MMP promoter activity occurred post-MI, and increased myocardial MT1-MMP levels resulted in poor survival, worsening of LV function, and significant fibrosis. A molecular mechanism for the adverse LV matrix remodeling with MT1-MMP induction is increased processing of pro-fibrotic signaling molecules. Thus, a proteolytically diverse portfolio exists for MT1-MMP within the myocardium and likely plays a mechanistic role in adverse LV remodeling.     

Lipopolysaccharide changes the subcellular distribution of aquaporin 5 and increases plasma membrane water permeability in mouse lung epithelial cells

Aquaporin-5 (AQP5), a major water channel in lung epithelial cells, plays an important role in maintaining water homeostasis in the lungs. Cell surface expression of AQP5 is regulated by not only mRNA and protein synthesis but also changes in subcellular distribution. We investigated the effect of lipopolysaccharide (LPS) on the subcellular distribution of AQP5 in a mouse lung epithelial cell line (MLE-12). LPS caused significant increases in AQP5 in the plasma membrane at 0.5-2 h. Immunofluorescence and Western blotting strongly suggested that LPS altered AQP5 subcellular distribution from an intracellular vesicular compartment to the plasma membrane. The specific p38 MAP kinase inhibitor SB 203580 apparently prevented LPS-induced changes in AQP5 distribution. Furthermore, LPS increased the osmotic water permeability of MLE-12 cells. These findings demonstrate that LPS increases cell surface AQP5 expression by changing its subcellular distribution and increases membrane osmotic water permeability through activation of p38 MAP kinase.     

冠状静脉窦逆行灌注和冠状动脉桥灌注在心脏外科手术的应用

目的总结和分析心脏外科手术中应用冠状动脉顺行灌注联合冠状静脉窦逆行灌注和冠状动脉桥灌注技术进行心肌保护。方法30例患者分为2组:A组(顺灌联合逆灌技术)20例和B组(顺逆灌结合桥灌技术)10例,疾病种类有:冠心病合并瓣膜病、冠心病合并室壁瘤、升主动脉病变合并主动脉瓣病变和单纯瓣膜病变。结果术中转流平稳,血流动力学稳定,监测指标均在正常范围,无手术死亡和围手术期并发症。结论采用冠状动脉顺行灌注联合冠状静脉窦逆行灌注或结合冠状动脉桥灌注心肌停搏液进行心肌保护,取得良好效果。     

Specificity of the accumulation of mRNAs and proteins of the plasma membrane and tonoplast aquaporins in radish organs

Plant aquaporins occur in multiple isoforms and are distributed in both plasma membrane and tonoplast. We cloned cDNAs for plasma-membrane aquaporins (PAQ1, 1b, 1c, 2, 2b, and 2c) of radish (Raphanus sativus L.). The amino acid sequences of the PAQs showed on average 63% sequence identity. Their sequences were 23% identical to those of tonoplast aquaporins (γ- and δ-VM23). A comprehensive investigation of the aquaporin mRNAs, including VM23, in seedlings, plants, flowers and seeds of radish showed a marked accumulation of all the mRNAs in hypocotyls and growing taproots. In other organs, the mRNA level of each isoform varied according to the organ. In petals, stamens, pistils and sepals of flowers, the levels of PAQ1, 1b, 1c and γ-VM23 mRNAs were high, and mRNAs of all aquaporins except for δ-VM23 were detected at high levels in pericarps. The protein levels of aquaporins on the basis of the membrane protein were determined by immunoblotting. Proteins PAQ1 and VM23 were detected in every organ except for the mature petiole. The PAQ2 protein level was especially high in green cotyledons and leaves, but was extremely low in seedling cotyledons and hypocotyls. Proteins PAQ1, PAQ2 and VM23 were highly accumulated in growing pericarps, but not in the immature seeds. These results indicate that the gene expression of the aquaporin isoforms was individually regulated in an organ- and tissue-specific manner, and that the amounts of aquaporin protein, especially PAQ2, are regulated in certain tissues at the translational level and by the rate of protein turnover. Received: 10 February 2000 / Accepted: 30 June 2000     

右美托咪定在体外循环下心内直视手术患儿肺保护、心肌保护的作用及对应激反应的影响

目的:探讨右美托咪定对体外循环(CPB)下心内直视手术患儿肺保护、心肌保护的作用及对应激反应的影响。方法:选取2017年3月～2019年9月期间我院收治的CPB下行室间隔缺损修补术患儿80例,上述患儿根据随机数字表法分为对照组(n=40)和研究组(n=40),麻醉诱导后研究组给予右美托咪定维持至术毕,对照组给予等容量生理盐水。比较两组患儿麻醉诱导前(T1)、停机后6h(T2)、停机后24h(T3)的肺功能[呼吸指数(RI)、氧合指数(OI)和肺顺应性(CL)]、心肌功能[心肌肌钙蛋白I(cTnI)、缺铁修饰白蛋白(IMA)]、炎性因子[白介素-6(IL-6)、肿瘤坏死因子-α(TNF-α)、白介素-1β(IL-1β)]及应激反应[皮质醇(Cor)、血糖(Glu)、去甲肾上腺素(NE)和肾上腺素(E)]情况。结果:两组T2～T3时间点RI呈下降趋势,且研究组低于对照组(P0.05),两组T2～T3时间点OI、CL呈升高趋势,且研究组高于对照组(P0.05)。两组T2～T3时间点cTnI、IMA呈下降趋势,且研究组低于对照组(P0.05)。两组T2～T3时间点Cor、Glu、NE、E呈下降趋势,且研究组低于对照组(P0.05)。两组T2～T3时间点IL-6、TNF-α、IL-1β呈下降趋势,且研究组低于对照组(P0.05)。结论:CPB下心内直视手术患儿术中予以右美托咪定,可有效保护其肺功能、心肌功能,减轻机体应激反应及炎性刺激,有一定的临床应用价值。     

Active water selective channels in the stomach: investigation of aquaporins after ethanol and capsaicin treatment in rats

Recent studies discovered the existence of aquaporins (AQP), suggesting their roles in the active, ATP dependent water secretion or absorption. Our recent development of the monoclonal antibody family against aquaporins (Type 1 and 4) allowed us a good opportunity to investigate the mechanism of the gastric mucosal edema in a rat model. THE AIM OF OUR STUDY was to evaluate the changes in the tissue level of aquaporins (AQP1 and AQP4) after ethanol and capsaicin treatment in rat stomach. MATERIALS AND METHODS: the experiments were carried out on Sprague-Dawley rats weighing 150-200 g. The animals were fasted for 24 h, after the 1 ml of ethanol (50% v/v) or capsaicin (2 mg/ml) was given intragastrically. Rats were sacrificed after 5, 30, 60, 120 and 240 min, the tissue level of AQP1 and AQP4 was investigated immunoserologically by ELISA and dot-blot methods using our monoclonal antibodies. The location of these aquaporins in the gastric tissue was demonstrated by immunohistochemistry. RESULTS: (1) in ethanol-treated stomach, both AQP1 and AQP4 increased after 5 min simultaneously with gastritis, then decreased dramatically depending on time. (2) In the capsaicin-treated group there were no changes in the tissue level of aquaporins in the first hour. After 60 min both AQP1 and AQP4 increased in the stomach without any macroscopically detectable changes, then decreased depending on time. (3) The immunohistochemical investigations using our monoclonal antibodies seem to support our present quantitative results. CONCLUSION: chemically induced gastric mucosal lesions are started by an extended edema. In the induction of the edema and the subsequent gastric injury, aquaporins (both AQP1 and AQP4) play an important role in the maintenance of mucosal integrity.     

Tissue and cell-specific localization of rice aquaporins and their water transport activities

Water transport in plants is greatly dependent on the expression and activity of water transport channels, called aquaporins. Here, we have clarified the tissue- and cell-specific localization of aquaporins in rice plants by immunoblotting and immunocytochemistry using seven isoform-specific aquaporin antibodies. We also examined water transport activities of typical aquaporin family members using a yeast expression system in combination with a stopped-flow spectrophotometry assay. OsPIP1 members, OsPIP2;1, OsTIP1;1 and OsTIP2;2 were expressed in both leaf blades and roots, while OsPIP2;3, OsPIP2;5 and OsTIP2;1 were expressed only in roots. In roots, large amounts of aquaporins accumulated in the region adjacent to the root tip (around 1.5-4 mm from the root tip). In this region, cell-specific localization of the various aquaporin members was observed. OsPIP1 members and OsTIP2;2 accumulated predominantly in the endodermis and the central cylinder, respectively. OsTIP1;1 showed specific localization in the rhizodermis and exodermis. OsPIP2;1, OsPIP2;3 and OsPIP2;5 accumulated in all root cells, but they showed higher levels of accumulation in endodermis than other cells. In the region at 35 mm from the root tip, where aerenchyma develops, aquaporins accumulated at low levels. In leaf blades, OsPIP1 members and OsPIP2;1 were localized mainly in mesophyll cells. OsPIP2;1, OsPIP2;3, OsPIP2;5 and OsTIP2;2 expressed in yeast showed high water transport activities. These results suggest that rice aquaporins with various water transport activities may play distinct roles in facilitating water flux and maintaining the water potential in different tissues and cells.     

The NPC motif of aquaporin-11, unlike the NPA motif of known aquaporins, is essential for full expression of molecular function

The recently identified molecule aquaporin-11 (AQP11) has a unique amino acid sequence pattern that includes an Asn-Pro-Cys (NPC) motif, corresponding to the N-terminal Asn-Pro-Ala (NPA) signature motif of conventional AQPs. In this study, we examined the effect of the mutation of the NPC motif on the subcellular localization, oligomerization, and water permeability of AQP11 in transfected mammalian cells. Furthermore, the effect was also assessed using zebrafish. Site-directed mutation at the NPC motif did not affect the subcellular localization of AQP11 but reduced its oligomerization. A cell swelling assay revealed that cells expressing AQP11 with a mutated NPC motif had significantly lower osmotic water permeability than cells expressing wild-type AQP11. Zebrafish deficient in endogenous AQP11 showed a deformity in the tail region at an early stage of development. This phenotype was dramatically rescued by injection of human wild-type AQP11 mRNA, whereas the effect of mRNA for AQP11 with a mutated NPC motif was less marked. Although the NPA motif is known to be important for formation of water-permeable pores by conventional AQPs, our observations suggest that the corresponding NPC motif of AQP11 is essential for full expression of molecular function.     

The influence of natural mineral water on aquaporin water permeability and human natural killer cell activity

Aquaporins are the intrinsic membrane proteins functioning as water channel to transport water and/or mineral nutrients across the biological membrane systems. In this research, we aimed to clarify if the selected mineral water can affect aquaporin functions in vitro and the assumption of the mineral water can modify aquaporin expression and activate natural killer cell activity in human body. First, we expressed six human and eight plant aquaporin genes in oocytes and compared the effect of different kinds of natural mineral water on aquaporin activity. The oocyte assay data show that Hita tenryosui water could promote water permeability of almost all human and plant aquaporins in varying degrees, and freeze-dry and organic solvent extraction could reduce AQP2 activity but pH change and boiling could not. Second, each volunteer in two groups (10 in one group) received an oral Hita tenryosui or tap water load of 1000 ml/day for total four weeks. We found that these two kinds of water did not directly affect the relative expression levels of AQP1 and AQP9 in the blood cells, but intriguingly, the natural killer cell activities of the volunteers drinking Hita tenryosui water were significantly improved, suggesting that Hita tenryosui water has obvious health function, which opens a new and interesting field of investigation related to the link between mineral water consumption and human health and the therapies for some chronic diseases.     

右美托咪定联合丙泊酚对体外循环下心脏瓣膜置换术患者心肌损伤、肾功能和细胞免疫功能的影响

摘要 目的：观察右美托咪定联合丙泊酚对体外循环（CPB）下心脏瓣膜置换术患者心肌损伤、肾功能和细胞免疫功能的影响。方法：回顾性分析2020年1月~2020年12月期间新疆医科大学第一附属医院收治的120例CPB下心脏瓣膜置换术患者的临床资料,根据麻醉方案的不同将患者分为对照组和研究组,各为60例,对照组患者接受丙泊酚麻醉,研究组患者接受右美托咪定联合丙泊酚麻醉。观察两组患者围术期指标、血流动力学、心肌损伤、肾功能和细胞免疫功能变化情况,记录两组围术期不良反应发生情况。结果：研究组患者的心脏复跳时间、术后苏醒时间、术后拔管时间、ICU滞留时间、术后住院时间均短于对照组患者（P<0.05）。术前（T0）~术毕（T3）时间点,两组患者的平均动脉压（MAP）、心率（HR）先下降后升高,肌酸激酶同工酶（CK-MB）和肌钙蛋白I（cTnI）水平则持续升高（P<0.05）,但CPB开始后30 min（T1）~ T3时间点,研究组患者的MAP、HR高于对照组患者,CK-MB、cTnI水平则低于对照组患者（P<0.05）。两组患者T0、术中、术后24 h 的尿素氮（BUN）、血清胱抑素C（CysC）水平呈升高趋势（P<0.05）。术中、术后24 h两组患者的CD4⁺、CD4⁺/CD8⁺均较T0下降,但研究组高于对照组（P<0.05）;术中、术后24 h两组患者的CD8⁺较T0升高,但研究组低于对照组（P<0.05）。两组不良反应发生率对比无统计学差异（P>0.05）。结论：右美托咪定联合丙泊酚应用于CPB下心脏瓣膜置换术患者,可减轻心肌损伤和细胞免疫功能抑制,维持血流动力学稳定,且不增加肾功能损伤和不良反应发生率。     

急性ST段抬高型心肌梗死患者术后碎裂QRS波的影响因素及其与心肌灌注和短期预后的关系分析

摘要 目的：探讨急性ST段抬高型心肌梗死（STEMI）患者术后碎裂QRS波（fQRS）的影响因素,分析其与心肌灌注及短期预后的关系。方法：选取上海中医药大学附属曙光医院宝山分院于2017年4月～2019年4月期间收治的108例STEMI患者的临床资料行回顾性研究,术后均行12导联心电图检查,根据有无fQRS,分成fQRS组（n=52）,非fQRS组（n=56）。比较两组临床资料,经单因素及多因素Logistic回归分析明确患者术后fQRS的影响因素。比较两组心肌灌注情况,心肌灌注采用心肌呈色分级法（MBG）进行分析。随访1年,分析患者主要不良心血管事件发生率,包括心力衰竭、心绞痛、心源性死亡、心源性休克,用于评价短期预后。结果：单因素分析提示,年龄、冠脉血管病变支数、Gensini评分、心绞痛发作至血管开通时间与术后fQRS有关（P＜0.05）。多因素Logistic回归分析显示,年龄、冠脉血管病变支数、Gensini评分、心绞痛发作至血管开通时间为术后fQRS的影响因素（P＜0.05）。fQRS组MBG 3级占比为46.15%,显著低于非fQRS组的76.79%（P＜0.05）。fQRS组不良心血管事件发生率为26.92%,显著高于非fQRS组的10.71%（P＜0.05）。结论：STEMI患者术后fQRS发生的影响因素包括年龄、冠脉血管病变支数、Gensini评分以及心绞痛发作至血管开通时间,且术后fQRS可预测心肌灌注情况及增加不良心血管事件发生率。     

A smoke-derived butenolide alleviates HgCl2 and ZnCl2 inhibition of water uptake during germination and subsequent growth of tomato--possible involvement of aquaporins

Aquaporins, concentrated in zones of cell division and enlargement, play a major role in governing the movement of water between neighboring cells during seed germination. The enhanced germination and growth found with smoke-water and butenolide could be the result of better water uptake, suggesting the involvement of aquaporins. The effects of butenolide, known aquaporin inhibitors (HgCl(2) and ZnCl(2)), along with several chemical agents known to reverse the inhibitory effects of mercuric chloride on the activity of aquaporins were tested. Seedlings raised in the presence of butenolide had higher moisture content (93%) compared to those imbibed in water only (85%). This suggests enhanced activity of aquaporins. The presence of aquaporin inhibitors (HgCl(2) and ZnCl(2)) reduced seedling water content and altered root development. The presence of HgCl(2) (10, 20 or 30muM) reduced the percentage imbibition of seeds by 11-12%. A corresponding gradual decline, from 17.5% (10muM) to 22.6% (30muM) (p0.05), in the root length was recorded. Addition of dithiothreitol (DTT, 500muM), beta-mercaptoethanol (ME, 250muM) and butenolide (0.1muM) along with the HgCl(2) overcame the observed inhibitory effects. The presence of ZnCl(2) (12.5 or 25muM) affected percentage imbibition as well as root length, which was reversed to some extent following addition of the butenolide. Though zinc chloride-mediated inhibition remained unaffected by the presence of DTT and ME, the butenolide reversed the effect. These results are interesting as they suggest additional avenues of research for uncovering the profound effect butenolide has on germination and growth.